#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef _MSC_VER #include #endif #include #include namespace internal { // @param m `1 <= m` // @return x mod m constexpr long long safe_mod(long long x, long long m) { x %= m; if (x < 0) x += m; return x; } // Fast modular multiplication by barrett reduction // Reference: https://en.wikipedia.org/wiki/Barrett_reduction // NOTE: reconsider after Ice Lake struct barrett { unsigned int _m; unsigned long long im; // @param m `1 <= m < 2^31` explicit barrett(unsigned int m) : _m(m), im((unsigned long long)(-1) / m + 1) {} // @return m unsigned int umod() const { return _m; } // @param a `0 <= a < m` // @param b `0 <= b < m` // @return `a * b % m` unsigned int mul(unsigned int a, unsigned int b) const { // [1] m = 1 // a = b = im = 0, so okay // [2] m >= 2 // im = ceil(2^64 / m) // -> im * m = 2^64 + r (0 <= r < m) // let z = a*b = c*m + d (0 <= c, d < m) // a*b * im = (c*m + d) * im = c*(im*m) + d*im = c*2^64 + c*r + d*im // c*r + d*im < m * m + m * im < m * m + 2^64 + m <= 2^64 + m * (m + 1) < // 2^64 * 2 // ((ab * im) >> 64) == c or c + 1 unsigned long long z = a; z *= b; #ifdef _MSC_VER unsigned long long x; _umul128(z, im, &x); #else unsigned long long x = (unsigned long long)(((unsigned __int128)(z)*im) >> 64); #endif unsigned int v = (unsigned int)(z - x * _m); if (_m <= v) v += _m; return v; } }; // @param n `0 <= n` // @param m `1 <= m` // @return `(x ** n) % m` constexpr long long pow_mod_constexpr(long long x, long long n, int m) { if (m == 1) return 0; unsigned int _m = (unsigned int)(m); unsigned long long r = 1; unsigned long long y = safe_mod(x, m); while (n) { if (n & 1) r = (r * y) % _m; y = (y * y) % _m; n >>= 1; } return r; } // Reference: // M. Forisek and J. Jancina, // Fast Primality Testing for Integers That Fit into a Machine Word // @param n `0 <= n` constexpr bool is_prime_constexpr(int n) { if (n <= 1) return false; if (n == 2 || n == 7 || n == 61) return true; if (n % 2 == 0) return false; long long d = n - 1; while (d % 2 == 0) d /= 2; constexpr long long bases[3] = {2, 7, 61}; for (long long a : bases) { long long t = d; long long y = pow_mod_constexpr(a, t, n); while (t != n - 1 && y != 1 && y != n - 1) { y = y * y % n; t <<= 1; } if (y != n - 1 && t % 2 == 0) { return false; } } return true; } template constexpr bool is_prime = is_prime_constexpr(n); // @param b `1 <= b` // @return pair(g, x) s.t. g = gcd(a, b), xa = g (mod b), 0 <= x < b/g constexpr std::pair inv_gcd(long long a, long long b) { a = safe_mod(a, b); if (a == 0) return {b, 0}; // Contracts: // [1] s - m0 * a = 0 (mod b) // [2] t - m1 * a = 0 (mod b) // [3] s * |m1| + t * |m0| <= b long long s = b, t = a; long long m0 = 0, m1 = 1; while (t) { long long u = s / t; s -= t * u; m0 -= m1 * u; // |m1 * u| <= |m1| * s <= b // [3]: // (s - t * u) * |m1| + t * |m0 - m1 * u| // <= s * |m1| - t * u * |m1| + t * (|m0| + |m1| * u) // = s * |m1| + t * |m0| <= b auto tmp = s; s = t; t = tmp; tmp = m0; m0 = m1; m1 = tmp; } // by [3]: |m0| <= b/g // by g != b: |m0| < b/g if (m0 < 0) m0 += b / s; return {s, m0}; } // Compile time primitive root // @param m must be prime // @return primitive root (and minimum in now) constexpr int primitive_root_constexpr(int m) { if (m == 2) return 1; if (m == 167772161) return 3; if (m == 469762049) return 3; if (m == 754974721) return 11; if (m == 998244353) return 3; int divs[20] = {}; divs[0] = 2; int cnt = 1; int x = (m - 1) / 2; while (x % 2 == 0) x /= 2; for (int i = 3; (long long)(i)*i <= x; i += 2) { if (x % i == 0) { divs[cnt++] = i; while (x % i == 0) { x /= i; } } } if (x > 1) { divs[cnt++] = x; } for (int g = 2;; g++) { bool ok = true; for (int i = 0; i < cnt; i++) { if (pow_mod_constexpr(g, (m - 1) / divs[i], m) == 1) { ok = false; break; } } if (ok) return g; } } template constexpr int primitive_root = primitive_root_constexpr(m); // @param n `n < 2^32` // @param m `1 <= m < 2^32` // @return sum_{i=0}^{n-1} floor((ai + b) / m) (mod 2^64) unsigned long long floor_sum_unsigned(unsigned long long n, unsigned long long m, unsigned long long a, unsigned long long b) { unsigned long long ans = 0; while (true) { if (a >= m) { ans += n * (n - 1) / 2 * (a / m); a %= m; } if (b >= m) { ans += n * (b / m); b %= m; } unsigned long long y_max = a * n + b; if (y_max < m) break; // y_max < m * (n + 1) // floor(y_max / m) <= n n = (unsigned long long)(y_max / m); b = (unsigned long long)(y_max % m); std::swap(m, a); } return ans; } } // namespace internal namespace internal { #ifndef _MSC_VER template using is_signed_int128 = typename std::conditional::value || std::is_same::value, std::true_type, std::false_type>::type; template using is_unsigned_int128 = typename std::conditional::value || std::is_same::value, std::true_type, std::false_type>::type; template using make_unsigned_int128 = typename std::conditional::value, __uint128_t, unsigned __int128>; template using is_integral = typename std::conditional::value || is_signed_int128::value || is_unsigned_int128::value, std::true_type, std::false_type>::type; template using is_signed_int = typename std::conditional<(is_integral::value && std::is_signed::value) || is_signed_int128::value, std::true_type, std::false_type>::type; template using is_unsigned_int = typename std::conditional<(is_integral::value && std::is_unsigned::value) || is_unsigned_int128::value, std::true_type, std::false_type>::type; template using to_unsigned = typename std::conditional< is_signed_int128::value, make_unsigned_int128, typename std::conditional::value, std::make_unsigned, std::common_type>::type>::type; #else template using is_integral = typename std::is_integral; template using is_signed_int = typename std::conditional::value && std::is_signed::value, std::true_type, std::false_type>::type; template using is_unsigned_int = typename std::conditional::value && std::is_unsigned::value, std::true_type, std::false_type>::type; template using to_unsigned = typename std::conditional::value, std::make_unsigned, std::common_type>::type; #endif template using is_signed_int_t = std::enable_if_t::value>; template using is_unsigned_int_t = std::enable_if_t::value>; template using to_unsigned_t = typename to_unsigned::type; } // namespace internal namespace internal { struct modint_base {}; struct static_modint_base : modint_base {}; template using is_modint = std::is_base_of; template using is_modint_t = std::enable_if_t::value>; } // namespace internal template * = nullptr> struct static_modint : internal::static_modint_base { using mint = static_modint; public: static constexpr int mod() { return m; } static mint raw(int v) { mint x; x._v = v; return x; } static_modint() : _v(0) {} template * = nullptr> static_modint(T v) { long long x = (long long)(v % (long long)(umod())); if (x < 0) x += umod(); _v = (unsigned int)(x); } template * = nullptr> static_modint(T v) { _v = (unsigned int)(v % umod()); } unsigned int val() const { return _v; } mint& operator++() { _v++; if (_v == umod()) _v = 0; return *this; } mint& operator--() { if (_v == 0) _v = umod(); _v--; return *this; } mint operator++(int) { mint result = *this; ++*this; return result; } mint operator--(int) { mint result = *this; --*this; return result; } mint& operator+=(const mint& rhs) { _v += rhs._v; if (_v >= umod()) _v -= umod(); return *this; } mint& operator-=(const mint& rhs) { _v -= rhs._v; if (_v >= umod()) _v += umod(); return *this; } mint& operator*=(const mint& rhs) { unsigned long long z = _v; z *= rhs._v; _v = (unsigned int)(z % umod()); return *this; } mint& operator/=(const mint& rhs) { return *this = *this * rhs.inv(); } mint operator+() const { return *this; } mint operator-() const { return mint() - *this; } mint pow(long long n) const { assert(0 <= n); mint x = *this, r = 1; while (n) { if (n & 1) r *= x; x *= x; n >>= 1; } return r; } mint inv() const { if (prime) { assert(_v); return pow(umod() - 2); } else { auto eg = internal::inv_gcd(_v, m); assert(eg.first == 1); return eg.second; } } friend mint operator+(const mint& lhs, const mint& rhs) { return mint(lhs) += rhs; } friend mint operator-(const mint& lhs, const mint& rhs) { return mint(lhs) -= rhs; } friend mint operator*(const mint& lhs, const mint& rhs) { return mint(lhs) *= rhs; } friend mint operator/(const mint& lhs, const mint& rhs) { return mint(lhs) /= rhs; } friend bool operator==(const mint& lhs, const mint& rhs) { return lhs._v == rhs._v; } friend bool operator!=(const mint& lhs, const mint& rhs) { return lhs._v != rhs._v; } private: unsigned int _v; static constexpr unsigned int umod() { return m; } static constexpr bool prime = internal::is_prime; }; template struct dynamic_modint : internal::modint_base { using mint = dynamic_modint; public: static int mod() { return (int)(bt.umod()); } static void set_mod(int m) { assert(1 <= m); bt = internal::barrett(m); } static mint raw(int v) { mint x; x._v = v; return x; } dynamic_modint() : _v(0) {} template * = nullptr> dynamic_modint(T v) { long long x = (long long)(v % (long long)(mod())); if (x < 0) x += mod(); _v = (unsigned int)(x); } template * = nullptr> dynamic_modint(T v) { _v = (unsigned int)(v % mod()); } unsigned int val() const { return _v; } mint& operator++() { _v++; if (_v == umod()) _v = 0; return *this; } mint& operator--() { if (_v == 0) _v = umod(); _v--; return *this; } mint operator++(int) { mint result = *this; ++*this; return result; } mint operator--(int) { mint result = *this; --*this; return result; } mint& operator+=(const mint& rhs) { _v += rhs._v; if (_v >= umod()) _v -= umod(); return *this; } mint& operator-=(const mint& rhs) { _v += mod() - rhs._v; if (_v >= umod()) _v -= umod(); return *this; } mint& operator*=(const mint& rhs) { _v = bt.mul(_v, rhs._v); return *this; } mint& operator/=(const mint& rhs) { return *this = *this * rhs.inv(); } mint operator+() const { return *this; } mint operator-() const { return mint() - *this; } mint pow(long long n) const { assert(0 <= n); mint x = *this, r = 1; while (n) { if (n & 1) r *= x; x *= x; n >>= 1; } return r; } mint inv() const { auto eg = internal::inv_gcd(_v, mod()); assert(eg.first == 1); return eg.second; } friend mint operator+(const mint& lhs, const mint& rhs) { return mint(lhs) += rhs; } friend mint operator-(const mint& lhs, const mint& rhs) { return mint(lhs) -= rhs; } friend mint operator*(const mint& lhs, const mint& rhs) { return mint(lhs) *= rhs; } friend mint operator/(const mint& lhs, const mint& rhs) { return mint(lhs) /= rhs; } friend bool operator==(const mint& lhs, const mint& rhs) { return lhs._v == rhs._v; } friend bool operator!=(const mint& lhs, const mint& rhs) { return lhs._v != rhs._v; } private: unsigned int _v; static internal::barrett bt; static unsigned int umod() { return bt.umod(); } }; template internal::barrett dynamic_modint::bt(998244353); using modint998244353 = static_modint<998244353>; using modint1000000007 = static_modint<1000000007>; using modint = dynamic_modint<-1>; namespace internal { template using is_static_modint = std::is_base_of; template using is_static_modint_t = std::enable_if_t::value>; template struct is_dynamic_modint : public std::false_type {}; template struct is_dynamic_modint> : public std::true_type {}; template using is_dynamic_modint_t = std::enable_if_t::value>; } // namespace internal using mint = modint998244353; /* g++ -std=c++23 -O2 -Wall -Wextra A.cpp -o A ./A < input.in > output.out */ template struct Edge { CostType cost; int src, dst; explicit Edge(const int src, const int dst, const CostType cost = 0) : cost(cost), src(src), dst(dst) {} auto operator<=>(const Edge& x) const = default; }; template struct HeavyLightDecomposition { std::vector parent, subtree, id, inv, head; std::vector cost; explicit HeavyLightDecomposition( const std::vector>>& graph, const int root = 0) : graph(graph) { const int n = graph.size(); parent.assign(n, -1); subtree.assign(n, 1); dfs1(root); id.resize(n); inv.resize(n); head.assign(n, root); int cur_id = 0; dfs2(root, &cur_id); } template void update_v(int u, int v, const Fn f) const { while (true) { if (id[u] > id[v]) std::swap(u, v); f(std::max(id[head[v]], id[u]), id[v] + 1); if (head[u] == head[v]) break; v = parent[head[v]]; } } template T query_v(int u, int v, const F f, const G g, const T id_t) const { T left = id_t, right = id_t; while (true) { if (id[u] > id[v]) { std::swap(u, v); std::swap(left, right); } // 在 v 这一侧的链上,查询 [max(id[head[v]], id[u]), id[v]] 这些点 left = g(left, f(std::max(id[head[v]], id[u]), id[v] + 1)); if (head[u] == head[v]) break; v = parent[head[v]]; } return g(left, right); } template void update_subtree_v(const int ver, const Fn f) const { f(id[ver], id[ver] + subtree[ver]); } template T query_subtree_v(const int ver, const Fn f) const { return f(id[ver], id[ver] + subtree[ver]); } template void update_e(int u, int v, const Fn f) const { while (true) { if (id[u] > id[v]) std::swap(u, v); if (head[u] == head[v]) { f(id[u], id[v]); break; } else { f(id[head[v]] - 1, id[v]); v = parent[head[v]]; } } } template T query_e(int u, int v, const F f, const G g, const T id_t) const { T left = id_t, right = id_t; while (true) { if (id[u] > id[v]) { std::swap(u, v); std::swap(left, right); } if (head[u] == head[v]) { left = g(left, f(id[u], id[v])); break; } else { left = g(left, f(id[head[v]] - 1, id[v])); v = parent[head[v]]; } } return g(left, right); } template void update_subtree_e(const int ver, const Fn f) const { f(id[ver], id[ver] + subtree[ver] - 1); } template T query_subtree_e(const int ver, const Fn f) const { return f(id[ver], id[ver] + subtree[ver] - 1); } // 对树边 (u, v) 做一次单边更新:调用 f(pos) // 其中 pos 是该边在“边序列”里的唯一位置(本实现为 id[child] - 1)。 template void update_single_edge(int u, int v, const Fn& f) const { if (parent[u] == v) std::swap(u, v); const int pos = id[v] - 1; f(pos); } int lowest_common_ancestor(int u, int v) const { while (true) { if (id[u] > id[v]) std::swap(u, v); if (head[u] == head[v]) break; v = parent[head[v]]; } return u; } private: std::vector>> graph; void dfs1(const int ver) { for (int i = 0; std::cmp_less(i, graph[ver].size()); ++i) { Edge& e = graph[ver][i]; if (e.dst != parent[ver]) { parent[e.dst] = ver; dfs1(e.dst); subtree[ver] += subtree[e.dst]; if (subtree[e.dst] > subtree[graph[ver].front().dst]) { std::swap(e, graph[ver].front()); } } } } void dfs2(const int ver, int* cur_id) { id[ver] = (*cur_id)++; inv[id[ver]] = ver; for (const Edge& e : graph[ver]) { if (e.dst != parent[ver]) { head[e.dst] = (e.dst == graph[ver].front().dst ? head[ver] : e.dst); cost.emplace_back(e.cost); dfs2(e.dst, cur_id); } } } }; struct BitRank { // block: bit 列を管理, count: block ごとに立っている 1 の数を管理 std::vector block; std::vector count; BitRank() {} void resize(const unsigned int num) { block.resize(((num + 1) >> 6) + 1, 0); count.resize(block.size(), 0); } // i ビット目を val(0,1) にセット void set(const unsigned int i, const unsigned long long val) { block[i >> 6] |= (val << (i & 63)); } void build() { for (unsigned int i = 1; i < block.size(); i++) { count[i] = count[i - 1] + __builtin_popcountll(block[i - 1]); } } // [0, i) ビットの 1 の数 unsigned int rank1(const unsigned int i) const { return count[i >> 6] + __builtin_popcountll(block[i >> 6] & ((1ULL << (i & 63)) - 1ULL)); } // [i, j) ビットの 1 の数 unsigned int rank1(const unsigned int i, const unsigned int j) const { return rank1(j) - rank1(i); } // [0, i) ビットの 0 の数 unsigned int rank0(const unsigned int i) const { return i - rank1(i); } // [i, j) ビットの 0 の数 unsigned int rank0(const unsigned int i, const unsigned int j) const { return rank0(j) - rank0(i); } }; class WaveletMatrix { private: unsigned int height; std::vector B; std::vector pos; std::vector> rui; public: WaveletMatrix() {} WaveletMatrix(std::vector vec) : WaveletMatrix(vec, *std::max_element(vec.begin(), vec.end()) + 1) {} // sigma:文字の種類数 WaveletMatrix(std::vector vec, const unsigned int sigma) { init(vec, sigma); } void init(std::vector& vec, const unsigned int sigma) { height = (sigma == 1) ? 1 : (64 - __builtin_clzll(sigma - 1)); B.resize(height), pos.resize(height); std::vector A = vec; rui.resize(height + 1); for (unsigned int i = 0; i < height; ++i) { B[i].resize(vec.size()); for (unsigned int j = 0; j < vec.size(); ++j) { B[i].set(j, get(vec[j], height - i - 1)); } B[i].build(); auto it = stable_partition(vec.begin(), vec.end(), [&](int c) { return !get(c, height - i - 1); }); pos[i] = it - vec.begin(); } for (unsigned int i = 0; i <= height; ++i) { rui[i].resize(A.size() + 1); for (int j = 1; j <= A.size(); j++) { rui[i][j] = rui[i][j - 1] + A[j - 1]; } if (i == height) break; std::stable_partition(A.begin(), A.end(), [&](int c) { return !get(c, height - i - 1); }); } } // val の i ビット目の値を返す(0,1) int get(const int val, const int i) { return val >> i & 1; } // [l, r) の間に現れる値 val の数 int rank(const int val, const int l, const int r) { return rank(val, r) - rank(val, l); } // [0, i) の間に現れる値 val の数 int rank(int val, int i) { int p = 0; for (unsigned int j = 0; j < height; ++j) { if (get(val, height - j - 1)) { p = pos[j] + B[j].rank1(p); i = pos[j] + B[j].rank1(i); } else { p = B[j].rank0(p); i = B[j].rank0(i); } } return i - p; } // [l, r) の k(0,1,2...) 番目に小さい値を返す int quantile(int k, int l, int r) { int res = 0; for (unsigned int i = 0; i < height; ++i) { const int j = B[i].rank0(l, r); if (j > k) { l = B[i].rank0(l); r = B[i].rank0(r); } else { l = pos[i] + B[i].rank1(l); r = pos[i] + B[i].rank1(r); k -= j; res |= (1 << (height - i - 1)); } } return res; } long long topKsum(int k, int l, int r) { if (l == r) return 0LL; long long res = 0; int atai = 0; for (unsigned int i = 0; i < height; ++i) { const int j = B[i].rank0(l, r); if (j > k) { l = B[i].rank0(l); r = B[i].rank0(r); } else { int l2 = B[i].rank0(l); int r2 = B[i].rank0(r); res += rui[i + 1][r2] - rui[i + 1][l2]; l = pos[i] + B[i].rank1(l); r = pos[i] + B[i].rank1(r); k -= j; atai |= (1 << (height - i - 1)); } } res += (long long)atai * k; return res; } int rangefreq(const int i, const int j, const int a, const int b, const int l, const int r, const int x) { if (i == j || r <= a || b <= l) return 0; const int mid = (l + r) >> 1; if (a <= l && r <= b) { return j - i; } else { const int left = rangefreq(B[x].rank0(i), B[x].rank0(j), a, b, l, mid, x + 1); const int right = rangefreq(pos[x] + B[x].rank1(i), pos[x] + B[x].rank1(j), a, b, mid, r, x + 1); return left + right; } } // [l,r) で値が [a,b) 内に含まれる数を返す int rangefreq(const int l, const int r, const int a, const int b) { return rangefreq(l, r, a, b, 0, 1 << height, 0); } int rangemin(const int i, const int j, const int a, const int b, const int l, const int r, const int x, const int val) { if (i == j || r <= a || b <= l) return -1; if (r - l == 1) return val; const int mid = (l + r) >> 1; const int res = rangemin(B[x].rank0(i), B[x].rank0(j), a, b, l, mid, x + 1, val); if (res < 0) return rangemin(pos[x] + B[x].rank1(i), pos[x] + B[x].rank1(j), a, b, mid, r, x + 1, val + (1 << (height - x - 1))); else return res; } // [l,r) で値が [a,b) 内に最小の数を返す(数が存在しない場合は -1 を返す) int rangemin(int l, int r, int a, int b) { return rangemin(l, r, a, b, 0, 1 << height, 0, 0); } }; template struct LazySegmentTree { using Monoid = typename T::Monoid; using LazyMonoid = typename T::LazyMonoid; explicit LazySegmentTree(const int n) : LazySegmentTree(std::vector(n, T::m_id())) {} explicit LazySegmentTree(const std::vector& a) : n(a.size()), height(0) { while ((1 << height) < n) ++height; sz = 1 << height; lazy.assign(sz, T::lazy_id()); data.assign(sz << 1, T::m_id()); std::copy(a.begin(), a.end(), data.begin() + sz); for (int i = sz - 1; i > 0; --i) { data[i] = T::m_merge(data[i << 1], data[(i << 1) + 1]); } } void set(int idx, const Monoid val) { idx += sz; for (int i = height; i > 0; --i) { propagate(idx >> i); } data[idx] = val; for (int i = 1; i <= height; ++i) { const int current_idx = idx >> i; data[current_idx] = T::m_merge(data[current_idx << 1], data[(current_idx << 1) + 1]); } } void apply(int idx, const LazyMonoid val) { idx += sz; for (int i = height; i > 0; --i) { propagate(idx >> i); } data[idx] = T::apply(data[idx], val); for (int i = 1; i <= height; ++i) { const int current_idx = idx >> i; data[current_idx] = T::m_merge(data[current_idx << 1], data[(current_idx << 1) + 1]); } } void apply(int left, int right, const LazyMonoid val) { if (right <= left) return; left += sz; right += sz; const int ctz_left = __builtin_ctz(left); for (int i = height; i > ctz_left; --i) { propagate(left >> i); } const int ctz_right = __builtin_ctz(right); for (int i = height; i > ctz_right; --i) { propagate(right >> i); } for (int l = left, r = right; l < r; l >>= 1, r >>= 1) { if (l & 1) apply_sub(l++, val); if (r & 1) apply_sub(--r, val); } for (int i = left >> (ctz_left + 1); i > 0; i >>= 1) { data[i] = T::m_merge(data[i << 1], data[(i << 1) + 1]); } for (int i = right >> (ctz_right + 1); i > 0; i >>= 1) { data[i] = T::m_merge(data[i << 1], data[(i << 1) + 1]); } } Monoid get(int left, int right) { if (right <= left) return T::m_id(); left += sz; right += sz; const int ctz_left = __builtin_ctz(left); for (int i = height; i > ctz_left; --i) { propagate(left >> i); } const int ctz_right = __builtin_ctz(right); for (int i = height; i > ctz_right; --i) { propagate(right >> i); } Monoid res_l = T::m_id(), res_r = T::m_id(); for (; left < right; left >>= 1, right >>= 1) { if (left & 1) res_l = T::m_merge(res_l, data[left++]); if (right & 1) res_r = T::m_merge(data[--right], res_r); } return T::m_merge(res_l, res_r); } Monoid operator[](const int idx) { const int node = idx + sz; for (int i = height; i > 0; --i) { propagate(node >> i); } return data[node]; } template int find_right(int left, const G g) { if (left >= n) return n; left += sz; for (int i = height; i > 0; --i) { propagate(left >> i); } Monoid val = T::m_id(); do { while (!(left & 1)) left >>= 1; Monoid nxt = T::m_merge(val, data[left]); if (!g(nxt)) { while (left < sz) { propagate(left); left <<= 1; nxt = T::m_merge(val, data[left]); if (g(nxt)) { val = nxt; ++left; } } return left - sz; } val = nxt; ++left; } while (__builtin_popcount(left) > 1); return n; } template int find_left(int right, const G g) { if (right <= 0) return -1; right += sz; for (int i = height; i > 0; --i) { propagate((right - 1) >> i); } Monoid val = T::m_id(); do { --right; while (right > 1 && (right & 1)) right >>= 1; Monoid nxt = T::m_merge(data[right], val); if (!g(nxt)) { while (right < sz) { propagate(right); right = (right << 1) + 1; nxt = T::m_merge(data[right], val); if (g(nxt)) { val = nxt; --right; } } return right - sz; } val = nxt; } while (__builtin_popcount(right) > 1); return -1; } const int n; int sz, height; std::vector data; std::vector lazy; void apply_sub(const int idx, const LazyMonoid& val) { data[idx] = T::apply(data[idx], val); if (idx < sz) lazy[idx] = T::lazy_merge(lazy[idx], val); } void propagate(const int idx) { apply_sub(idx << 1, lazy[idx]); apply_sub((idx << 1) + 1, lazy[idx]); lazy[idx] = T::lazy_id(); } }; namespace monoid { template struct RangeMinimumAndUpdateQuery { using Monoid = T; using LazyMonoid = T; static constexpr Monoid m_id() { return std::numeric_limits::max(); } static constexpr LazyMonoid lazy_id() { return std::numeric_limits::max(); } static Monoid m_merge(const Monoid& a, const Monoid& b) { return std::min(a, b); } static LazyMonoid lazy_merge(const LazyMonoid& a, const LazyMonoid& b) { return b == lazy_id() ? a : b; } static Monoid apply(const Monoid& a, const LazyMonoid& b) { return b == lazy_id() ? a : b; } }; template struct RangeMaximumAndUpdateQuery { using Monoid = T; using LazyMonoid = T; static constexpr Monoid m_id() { return std::numeric_limits::lowest(); } static constexpr LazyMonoid lazy_id() { return std::numeric_limits::lowest(); } static Monoid m_merge(const Monoid& a, const Monoid& b) { return std::max(a, b); } static LazyMonoid lazy_merge(const LazyMonoid& a, const LazyMonoid& b) { return b == lazy_id() ? a : b; } static Monoid apply(const Monoid& a, const LazyMonoid& b) { return b == lazy_id() ? a : b; } }; template struct RangeMinimumAndAddQuery { using Monoid = T; using LazyMonoid = T; static constexpr Monoid m_id() { return Inf; } static constexpr LazyMonoid lazy_id() { return 0; } static Monoid m_merge(const Monoid& a, const Monoid& b) { return std::min(a, b); } static LazyMonoid lazy_merge(const LazyMonoid& a, const LazyMonoid& b) { return a + b; } static Monoid apply(const Monoid& a, const LazyMonoid& b) { return a + b; } }; template struct RangeMaximumAndAddQuery { using Monoid = T; using LazyMonoid = T; static constexpr Monoid m_id() { return -Inf; } static constexpr LazyMonoid lazy_id() { return 0; } static Monoid m_merge(const Monoid& a, const Monoid& b) { return std::max(a, b); } static LazyMonoid lazy_merge(const LazyMonoid& a, const LazyMonoid& b) { return a + b; } static Monoid apply(const Monoid& a, const LazyMonoid& b) { return a + b; } }; template struct RangeSumAndUpdateQuery { using Monoid = struct { T sum; int len; }; using LazyMonoid = T; static std::vector init(const int n) { return std::vector(n, Monoid{0, 1}); } static constexpr Monoid m_id() { return {0, 0}; } static constexpr LazyMonoid lazy_id() { return std::numeric_limits::max(); } static Monoid m_merge(const Monoid& a, const Monoid& b) { return Monoid{a.sum + b.sum, a.len + b.len}; } static LazyMonoid lazy_merge(const LazyMonoid& a, const LazyMonoid& b) { return b == lazy_id() ? a : b; } static Monoid apply(const Monoid& a, const LazyMonoid& b) { return Monoid{b == lazy_id() ? a.sum : b * a.len, a.len}; } }; template struct RangeSumAndAddQuery { using Monoid = struct { T sum; int len; }; using LazyMonoid = T; static std::vector init(const int n) { return std::vector(n, Monoid{0, 1}); } static constexpr Monoid m_id() { return {0, 0}; } static constexpr LazyMonoid lazy_id() { return 0; } static Monoid m_merge(const Monoid& a, const Monoid& b) { return Monoid{a.sum + b.sum, a.len + b.len}; } static LazyMonoid lazy_merge(const LazyMonoid& a, const LazyMonoid& b) { return a + b; } static Monoid apply(const Monoid& a, const LazyMonoid& b) { return Monoid{a.sum + b * a.len, a.len}; } }; } // namespace monoid #pragma once // credit emthrm.github.io/library template struct SegmentTree { using Monoid = typename T::Monoid; explicit SegmentTree(int n) : SegmentTree(std::vector(n, T::id())) {} explicit SegmentTree(const std::vector& a) : n(a.size()), sz(1) { while (sz < n) sz <<= 1; data.assign(sz << 1, T::id()); std::copy(a.begin(), a.end(), data.begin() + sz); for (int i = sz - 1; i > 0; --i) { data[i] = T::merge(data[i << 1], data[(i << 1) + 1]); } } void set(int idx, const Monoid val) { idx += sz; data[idx] = val; while (idx >>= 1) data[idx] = T::merge(data[idx << 1], data[(idx << 1) + 1]); } Monoid get(int left, int right) const { Monoid res_l = T::id(), res_r = T::id(); for (left += sz, right += sz; left < right; left >>= 1, right >>= 1) { if (left & 1) res_l = T::merge(res_l, data[left++]); if (right & 1) res_r = T::merge(data[--right], res_r); } return T::merge(res_l, res_r); } Monoid operator[](const int idx) const { return data[idx + sz]; } private: const int n; int sz; // sz + 原数组坐标 = 线段树里的编号,1 based std::vector data; }; namespace monoid { template struct RangeMinimumQuery { using Monoid = T; static constexpr Monoid id() { return std::numeric_limits::max(); } static Monoid merge(const Monoid& a, const Monoid& b) { return std::min(a, b); } }; template struct RangeMaximumQuery { using Monoid = T; static constexpr Monoid id() { return std::numeric_limits::lowest(); } static Monoid merge(const Monoid& a, const Monoid& b) { return std::max(a, b); } }; template struct RangeSumQuery { using Monoid = T; static constexpr Monoid id() { return 0; } static Monoid merge(const Monoid& a, const Monoid& b) { return a + b; } }; template struct RangeXorQuery { using Monoid = T; static constexpr Monoid id() { return 0; } static Monoid merge(const Monoid& a, const Monoid& b) { return a ^ b; } }; } // namespace monoid struct TupleHash { template static void hash_combine(std::size_t& seed, const T& v) { seed ^= std::hash{}(v) + 0x9e3779b9 + (seed << 6) + (seed >> 2); } template std::size_t operator()(const std::tuple& t) const noexcept { std::size_t seed = 0; std::apply([&](const auto&... xs) { (hash_combine(seed, xs), ...); }, t); return seed; } }; // unordered_map, int, TupleHash> cnt; struct ChthollyNode { int l, r; mutable int v; ChthollyNode(int l, int r, int v) : l(l), r(r), v(v) {} bool operator<(const ChthollyNode& o) const { return l < o.l; } }; std::set tr; std::set::iterator split(int pos) { auto it = tr.lower_bound(ChthollyNode(pos, 0, 0)); if (it != tr.end() && it->l == pos) return it; it--; int l = it->l, r = it->r, v = it->v; tr.erase(it); tr.insert(ChthollyNode(l, pos - 1, v)); return tr.insert(ChthollyNode(pos, r, v)).first; } // range add void add(int l, int r, int v) { // [l, r] auto end = split(r + 1); for (auto it = split(l); it != end; it++) it->v += v; } // range assign void assign(int l, int r, int v) { auto end = split(r + 1), begin = split(l); // 顺序不能颠倒,否则可能RE tr.erase(begin, end); // 清除一系列节点 tr.insert(ChthollyNode(l, r, v)); // 插入新的节点 } // range kth int kth(int l, int r, int k) { auto end = split(r + 1); std::vector> v; // 这个pair里存节点的值和区间长度 for (auto it = split(l); it != end; it++) v.emplace_back(it->v, it->r - it->l + 1); std::sort(v.begin(), v.end()); // 直接按节点的值的大小排下序 for (int i = 0; i < v.size(); i++) // 然后挨个丢出来,直到丢出k个元素为止 { k -= v[i].second; if (k <= 0) return v[i].first; } } int ones = 0; // 全局变量,记录当前数组中 1 的个数 void range_xor(int l, int r) { auto itR = split(r + 1); for (auto it = split(l); it != itR; ++it) { int len = it->r - it->l + 1; ones += (it->v ? -len : +len); it->v ^= 1; } } void paint_black(int l, int r) { auto itR = split(r + 1); auto itL = split(l); for (auto it = itL; it != itR; ++it) { if (it->v == 1) ones -= (it->r - it->l + 1); } tr.erase(itL, itR); tr.insert(ChthollyNode(l, r, 1)); ones += (r - l + 1); } struct EulerianTrailInUndirectedGraph { std::vector trail; explicit EulerianTrailInUndirectedGraph(const int n) : n(n), is_visited(n), graph(n) {} void add_edge(const int u, const int v) { graph[u].emplace_back(v, graph[v].size()); graph[v].emplace_back(u, graph[u].size() - 1); } bool build(int s = -1) { trail.clear(); int odd_deg = 0, edge_num = 0; for (int i = 0; i < n; ++i) { if (graph[i].size() & 1) { ++odd_deg; if (s == -1) s = i; } edge_num += graph[i].size(); } edge_num >>= 1; if (edge_num == 0) { trail = {s == -1 ? 0 : s}; return true; } if (odd_deg == 0) { if (s == -1) { s = std::distance( graph.begin(), std::find_if_not(graph.begin(), graph.end(), [](const std::vector& edges) -> bool { return edges.empty(); })); } } else if (odd_deg != 2) { return false; } for (int i = 0; i < n; ++i) { is_visited[i].assign(graph[i].size(), false); } dfs(s); if (std::cmp_equal(trail.size(), edge_num + 1)) { std::reverse(trail.begin(), trail.end()); return true; } trail.clear(); return false; } private: struct Edge { int dst, rev; explicit Edge(const int dst, const int rev) : dst(dst), rev(rev) {} }; const int n; std::vector> is_visited; std::vector> graph; void dfs(const int ver) { const int deg = graph[ver].size(); for (int i = 0; i < deg; ++i) { if (!is_visited[ver][i]) { const int dst = graph[ver][i].dst; is_visited[ver][i] = true; is_visited[dst][graph[ver][i].rev] = true; dfs(dst); } } trail.emplace_back(ver); } }; int main() { std::string s; std::cin >> s; int n = s.size(); std::vector a(13); for (int i = 0; i < n; i++) { a[s[i] - 'a']++; } bool happened = false; for (char c = 'a'; c <= 'm'; c++) { a[c - 'a'] += 1; int ones = 0; int two = 0; for (int i = 0; i < 13; i++) { if (a[i] == 1) { ones++; } else if (a[i] == 2) { two++; } } if (ones == 12 && two == 1) { std::cout << c << '\n'; happened = true; } a[c - 'a'] -= 1; } if (!happened) { std::cout << "Impossible\n"; } }