#include using i32 = int; using u32 = unsigned int; using i64 = long long; using u64 = unsigned long long; using i128 = __int128_t; using u128 = __uint128_t; using f64 = double; using f80 = long double; using f128 = __float128; constexpr i32 operator"" _i32(u64 v) { return v; } constexpr u32 operator"" _u32(u64 v) { return v; } constexpr i64 operator"" _i64(u64 v) { return v; } constexpr u64 operator"" _u64(u64 v) { return v; } constexpr f64 operator"" _f64(f80 v) { return v; } constexpr f80 operator"" _f80(f80 v) { return v; } using Istream = std::istream; using Ostream = std::ostream; using Str = std::string; template using Lt = std::less; template using Gt = std::greater; template using BSet = std::bitset; template using Pair = std::pair; template using Tup = std::tuple; template using Arr = std::array; template using Deq = std::deque; template using Set = std::set; template using MSet = std::multiset; template using USet = std::unordered_set; template using UMSet = std::unordered_multiset; template using Map = std::map; template using MMap = std::multimap; template using UMap = std::unordered_map; template using UMMap = std::unordered_multimap; template using Vec = std::vector; template using Stack = std::stack; template using Queue = std::queue; template using MaxHeap = std::priority_queue; template using MinHeap = std::priority_queue, Gt>; constexpr bool LOCAL = false; constexpr bool OJ = not LOCAL; template static constexpr T OjLocal(T oj, T local) { return LOCAL ? local : oj; } template constexpr T LIMMIN = std::numeric_limits::min(); template constexpr T LIMMAX = std::numeric_limits::max(); template constexpr T INF = (LIMMAX - 1) / 2; template constexpr T PI = T{3.141592653589793238462643383279502884}; template constexpr T TEN(int n) { return n == 0 ? T{1} : TEN(n - 1) * T{10}; } template constexpr bool chmin(T& a, const T& b) { return (a > b ? (a = b, true) : false); } template constexpr bool chmax(T& a, const T& b) { return (a < b ? (a = b, true) : false); } template constexpr T floorDiv(T x, T y) { assert(y != 0); if (y < 0) { x = -x, y = -y; } return x >= 0 ? x / y : (x - y + 1) / y; } template constexpr T ceilDiv(T x, T y) { assert(y != 0); if (y < 0) { x = -x, y = -y; } return x >= 0 ? (x + y - 1) / y : x / y; } template constexpr T powerMonoid(T v, I n, const T& e) { assert(n >= 0); if (n == 0) { return e; } return (n % 2 == 1 ? v * powerMonoid(v, n - 1, e) : powerMonoid(v * v, n / 2, e)); } template constexpr T powerInt(T v, I n) { return powerMonoid(v, n, T{1}); } template constexpr void fillAll(Vs& arr, const V& v) { if constexpr (std::is_convertible::value) { arr = v; } else { for (auto& subarr : arr) { fillAll(subarr, v); } } } template constexpr void sortAll(Vs& vs) { std::sort(std::begin(vs), std::end(vs)); } template constexpr void sortAll(Vs& vs, C comp) { std::sort(std::begin(vs), std::end(vs), comp); } template constexpr void reverseAll(Vs& vs) { std::reverse(std::begin(vs), std::end(vs)); } template constexpr Vs reversed(const Vs& vs) { auto rvs = vs; reverseAll(rvs); return rvs; } template constexpr V sumAll(const Vs& vs) { if constexpr (std::is_convertible::value) { return static_cast(vs); } else { V ans = 0; for (const auto& v : vs) { ans += sumAll(v); } return ans; } } template constexpr int minInd(const Vs& vs) { return std::min_element(std::begin(vs), std::end(vs)) - std::begin(vs); } template constexpr int maxInd(const Vs& vs) { return std::max_element(std::begin(vs), std::end(vs)) - std::begin(vs); } template constexpr int lbInd(const Vs& vs, const V& v) { return std::lower_bound(std::begin(vs), std::end(vs), v) - std::begin(vs); } template constexpr int ubInd(const Vs& vs, const V& v) { return std::upper_bound(std::begin(vs), std::end(vs), v) - std::begin(vs); } template constexpr void plusAll(Vs& vs, const V& v) { for (auto& v_ : vs) { v_ += v; } } template constexpr void concat(Vs& vs1, const Vs& vs2) { std::copy(std::begin(vs2), std::end(vs2), std::back_inserter(vs1)); } template constexpr void concatted(const Vs& vs1, const Vs& vs2) { auto vs = vs1; concat(vs, vs2); return vs; } template constexpr Vec genVec(int n, F gen) { Vec ans; std::generate_n(std::back_inserter(ans), n, gen); return ans; } template constexpr Vec iotaVec(int n, T offset = 0) { Vec ans(n); std::iota(std::begin(ans), std::end(ans), offset); return ans; } template constexpr void rearrange(Vs& vs, const Vec& is) { auto vs_ = vs; for (int i = 0; i < (int)is.size(); i++) { vs[i] = vs_[is[i]]; } } inline Vec reversePerm(const Vec& is) { auto ris = is; for (int i = 0; i < (int)is.size(); i++) { ris[is[i]] = i; } return ris; } inline Ostream& operator<<(Ostream& os, i128 v) { bool minus = false; if (v < 0) { minus = true, v = -v; } Str ans; if (v == 0) { ans = "0"; } while (v) { ans.push_back('0' + v % 10), v /= 10; } std::reverse(ans.begin(), ans.end()); return os << (minus ? "-" : "") << ans; } inline Ostream& operator<<(Ostream& os, u128 v) { Str ans; if (v == 0) { ans = "0"; } while (v) { ans.push_back('0' + v % 10), v /= 10; } std::reverse(ans.begin(), ans.end()); return os << ans; } constexpr int popCount(u64 v) { return v ? __builtin_popcountll(v) : 0; } constexpr int topBit(u64 v) { return v == 0 ? -1 : 63 - __builtin_clzll(v); } constexpr int lowBit(u64 v) { return v == 0 ? 64 : __builtin_ctzll(v); } constexpr int bitWidth(u64 v) { return topBit(v) + 1; } constexpr u64 bitCeil(u64 v) { return v ? (1_u64 << bitWidth(v - 1)) : 1_u64; } constexpr u64 bitFloor(u64 v) { return v ? (1_u64 << topBit(v)) : 0_u64; } constexpr bool hasSingleBit(u64 v) { return (v > 0) and ((v & (v - 1)) == 0); } constexpr bool isBitOn(u64 mask, int ind) { return (mask >> ind) & 1_u64; } constexpr bool isBitOff(u64 mask, int ind) { return not isBitOn(mask, ind); } constexpr u64 bitMask(int bitWidth) { return (bitWidth == 64 ? ~0_u64 : (1_u64 << bitWidth) - 1); } constexpr u64 bitMask(int start, int end) { return bitMask(end - start) << start; } template struct Fix : F { constexpr Fix(F&& f) : F{std::forward(f)} {} template constexpr auto operator()(Args&&... args) const { return F::operator()(*this, std::forward(args)...); } }; class irange { private: struct itr { constexpr itr(i64 start = 0, i64 step = 1) : m_cnt{start}, m_step{step} {} constexpr bool operator!=(const itr& it) const { return m_cnt != it.m_cnt; } constexpr i64 operator*() { return m_cnt; } constexpr itr& operator++() { return m_cnt += m_step, *this; } i64 m_cnt, m_step; }; i64 m_start, m_end, m_step; public: static constexpr i64 cnt(i64 start, i64 end, i64 step) { if (step == 0) { return -1; } const i64 d = (step > 0 ? step : -step); const i64 l = (step > 0 ? start : end); const i64 r = (step > 0 ? end : start); i64 n = (r - l) / d + ((r - l) % d ? 1 : 0); if (l >= r) { n = 0; } return n; } constexpr irange(i64 start, i64 end, i64 step = 1) : m_start{start}, m_end{m_start + step * cnt(start, end, step)}, m_step{step} { assert(step != 0); } constexpr itr begin() const { return itr{m_start, m_step}; } constexpr itr end() const { return itr{m_end, m_step}; } }; constexpr irange rep(i64 end) { return irange(0, end, 1); } constexpr irange per(i64 rend) { return irange(rend - 1, -1, -1); } class Scanner { public: Scanner(Istream& is = std::cin) : m_is{is} { m_is.tie(nullptr)->sync_with_stdio(false); } template T val() { T v; return m_is >> v, v; } template T val(T offset) { return val() - offset; } template Vec vec(int n) { return genVec(n, [&]() { return val(); }); } template Vec vec(int n, T offset) { return genVec(n, [&]() { return val(offset); }); } template Vec> vvec(int n, int m) { return genVec>(n, [&]() { return vec(m); }); } template Vec> vvec(int n, int m, const T offset) { return genVec>(n, [&]() { return vec(m, offset); }); } template auto tup() { return Tup{val()...}; } template auto tup(const Args&... offsets) { return Tup{val(offsets)...}; } private: Istream& m_is; }; inline Scanner in; class Printer { public: Printer(Ostream& os = std::cout) : m_os{os} { m_os << std::fixed << std::setprecision(15); } template int operator()(const Args&... args) { return dump(args...), 0; } template int ln(const Args&... args) { return dump(args...), m_os << '\n', 0; } template int el(const Args&... args) { return dump(args...), m_os << std::endl, 0; } int YES(bool b = true) { return ln(b ? "YES" : "NO"); } int NO(bool b = true) { return YES(not b); } int Yes(bool b = true) { return ln(b ? "Yes" : "No"); } int No(bool b = true) { return Yes(not b); } private: template void dump(const T& v) { m_os << v; } template void dump(const Vec& vs) { for (int i : rep(vs.size())) { m_os << (i ? " " : ""), dump(vs[i]); } } template void dump(const Vec>& vss) { for (int i : rep(vss.size())) { m_os << (i ? "\n" : ""), dump(vss[i]); } } template int dump(const T& v, const Ts&... args) { return dump(v), m_os << ' ', dump(args...), 0; } Ostream& m_os; }; inline Printer out; template auto ndVec(int const (&szs)[n], const T x = T{}) { if constexpr (i == n) { return x; } else { return std::vector(szs[i], ndVec(szs, x)); } } template inline T binSearch(T ng, T ok, F check) { while (std::abs(ok - ng) > 1) { const T mid = (ok + ng) / 2; (check(mid) ? ok : ng) = mid; } return ok; } template constexpr Pair extgcd(const T a, const T b) // [x,y] -> ax+by=gcd(a,b) { static_assert(std::is_signed_v, "Signed integer is allowed."); assert(a != 0 or b != 0); if (a >= 0 and b >= 0) { if (a < b) { const auto [y, x] = extgcd(b, a); return {x, y}; } if (b == 0) { return {1, 0}; } const auto [x, y] = extgcd(b, a % b); return {y, x - (a / b) * y}; } else { auto [x, y] = extgcd(std::abs(a), std::abs(b)); if (a < 0) { x = -x; } if (b < 0) { y = -y; } return {x, y}; } } template constexpr T inverse(const T a, const T mod) // ax=gcd(a,M) (mod M) { assert(a > 0 and mod > 0); auto [x, y] = extgcd(a, mod); if (x <= 0) { x += mod; } return x; } template class modint { template static U modRef() { static u32 s_mod = 0; return s_mod; } template static U rootRef() { static u32 s_root = 0; return s_root; } template static U max2pRef() { static u32 s_max2p = 0; return s_max2p; } public: static_assert(mod_ <= LIMMAX, "mod(signed int size) only supported!"); static constexpr bool isDynamic() { return (mod_ == 0); } template static constexpr std::enable_if_t mod() { return mod_; } template static std::enable_if_t mod() { return modRef(); } template static constexpr std::enable_if_t root() { return root_; } template static std::enable_if_t root() { return rootRef(); } template static constexpr std::enable_if_t max2p() { return max2p_; } template static std::enable_if_t max2p() { return max2pRef(); } template static void setMod(std::enable_if_t m) { assert(1 <= m and m <= LIMMAX); modRef() = m; sinvRef() = {1, 1}; factRef() = {1, 1}; ifactRef() = {1, 1}; } template static void setRoot(std::enable_if_t r) { rootRef() = r; } template static void setMax2p(std::enable_if_t m) { max2pRef() = m; } constexpr modint() : m_val{0} {} constexpr modint(i64 v) : m_val{normll(v)} {} constexpr void setRaw(u32 v) { m_val = v; } constexpr modint operator-() const { return modint{0} - (*this); } constexpr modint& operator+=(const modint& m) { m_val = norm(m_val + m.val()); return *this; } constexpr modint& operator-=(const modint& m) { m_val = norm(m_val + mod() - m.val()); return *this; } constexpr modint& operator*=(const modint& m) { m_val = normll((i64)m_val * (i64)m.val() % (i64)mod()); return *this; } constexpr modint& operator/=(const modint& m) { return *this *= m.inv(); } constexpr modint operator+(const modint& m) const { auto v = *this; return v += m; } constexpr modint operator-(const modint& m) const { auto v = *this; return v -= m; } constexpr modint operator*(const modint& m) const { auto v = *this; return v *= m; } constexpr modint operator/(const modint& m) const { auto v = *this; return v /= m; } constexpr bool operator==(const modint& m) const { return m_val == m.val(); } constexpr bool operator!=(const modint& m) const { return not(*this == m); } friend Istream& operator>>(Istream& is, modint& m) { i64 v; return is >> v, m = v, is; } friend Ostream& operator<<(Ostream& os, const modint& m) { return os << m.val(); } constexpr u32 val() const { return m_val; } template constexpr modint pow(I n) const { return powerInt(*this, n); } constexpr modint inv() const { return inverse(m_val, mod()); } static modint sinv(u32 n) { auto& is = sinvRef(); for (u32 i = (u32)is.size(); i <= n; i++) { is.push_back(-is[mod() % i] * (mod() / i)); } return is[n]; } static modint fact(u32 n) { auto& fs = factRef(); for (u32 i = (u32)fs.size(); i <= n; i++) { fs.push_back(fs.back() * i); } return fs[n]; } static modint ifact(u32 n) { auto& ifs = ifactRef(); for (u32 i = (u32)ifs.size(); i <= n; i++) { ifs.push_back(ifs.back() * sinv(i)); } return ifs[n]; } static modint perm(int n, int k) { return k > n or k < 0 ? modint{0} : fact(n) * ifact(n - k); } static modint comb(int n, int k) { return k > n or k < 0 ? modint{0} : fact(n) * ifact(n - k) * ifact(k); } private: static Vec& sinvRef() { static Vec is{1, 1}; return is; } static Vec& factRef() { static Vec fs{1, 1}; return fs; } static Vec& ifactRef() { static Vec ifs{1, 1}; return ifs; } static constexpr u32 norm(u32 x) { return x < mod() ? x : x - mod(); } static constexpr u32 normll(i64 x) { return norm(u32(x % (i64)mod() + (i64)mod())); } u32 m_val; }; using modint_1000000007 = modint<1000000007, 5, 1>; using modint_998244353 = modint<998244353, 3, 23>; template using modint_dynamic = modint<0, 0, id>; template class Graph { struct Edge { Edge() = default; Edge(int i, int t, T c) : id{i}, to{t}, cost{c} {} int id; int to; T cost; operator int() const { return to; } }; public: Graph(int n) : m_v{n}, m_edges(n) {} void addEdge(int u, int v, bool bi = false) { assert(0 <= u and u < m_v); assert(0 <= v and v < m_v); m_edges[u].emplace_back(m_e, v, 1); if (bi) { m_edges[v].emplace_back(m_e, u, 1); } m_e++; } void addEdge(int u, int v, const T& c, bool bi = false) { assert(0 <= u and u < m_v); assert(0 <= v and v < m_v); m_edges[u].emplace_back(m_e, v, c); if (bi) { m_edges[v].emplace_back(m_e, u, c); } m_e++; } const Vec& operator[](const int u) const { assert(0 <= u and u < m_v); return m_edges[u]; } Vec& operator[](const int u) { assert(0 <= u and u < m_v); return m_edges[u]; } int v() const { return m_v; } int e() const { return m_e; } friend Ostream& operator<<(Ostream& os, const Graph& g) { for (int u : rep(g.v())) { for (const auto& [id, v, c] : g[u]) { os << "[" << id << "]: "; os << u << "->" << v << "(" << c << ")\n"; } } return os; } Vec sizes(int root = 0) const { const int N = v(); assert(0 <= root and root < N); Vec ss(N, 1); Fix([&](auto dfs, int u, int p) -> void { for ([[maybe_unused]] const auto& [_temp_name_0, v, c] : m_edges[u]) { if (v == p) { continue; } dfs(v, u); ss[u] += ss[v]; } })(root, -1); return ss; } Vec depths(int root = 0) const { const int N = v(); assert(0 <= root and root < N); Vec ds(N, 0); Fix([&](auto dfs, int u, int p) -> void { for ([[maybe_unused]] const auto& [_temp_name_1, v, c] : m_edges[u]) { if (v == p) { continue; } ds[v] = ds[u] + c; dfs(v, u); } })(root, -1); return ds; } Vec parents(int root = 0) const { const int N = v(); assert(0 <= root and root < N); Vec ps(N, -1); Fix([&](auto dfs, int u, int p) -> void { for ([[maybe_unused]] const auto& [_temp_name_2, v, c] : m_edges[u]) { if (v == p) { continue; } ps[v] = u; dfs(v, u); } })(root, -1); return ps; } private: int m_v; int m_e = 0; Vec> m_edges; }; using namespace std; struct UnionFind { vector data; UnionFind() = default; explicit UnionFind(size_t sz) : data(sz, -1) {} bool unite(int x, int y) { x = find(x), y = find(y); if (x == y) return false; if (data[x] > data[y]) swap(x, y); data[x] += data[y]; data[y] = x; return true; } int find(int k) { if (data[k] < 0) return (k); return data[k] = find(data[k]); } int size(int k) { return -data[find(k)]; } bool same(int x, int y) { return find(x) == find(y); } vector> groups() { int n = (int)data.size(); vector> ret(n); for (int i = 0; i < n; i++) { ret[find(i)].emplace_back(i); } ret.erase(remove_if(begin(ret), end(ret), [&](const vector& v) { return v.empty(); }), end(ret)); return ret; } }; /** * @brief Bipartite Flow(二部グラフのフロー) * @docs docs/bipartite-flow.md */ struct BipartiteFlow { size_t n, m, time_stamp; vector> g, rg; vector match_l, match_r, dist, used, alive; bool matched; public: explicit BipartiteFlow(size_t n, size_t m) : n(n), m(m), time_stamp(0), g(n), rg(m), match_l(n, -1), match_r(m, -1), used(n), alive(n, 1), matched(false) {} void add_edge(int u, int v) { g[u].push_back(v); rg[v].emplace_back(u); } vector> max_matching() { matched = true; for (;;) { build_augment_path(); ++time_stamp; int flow = 0; for (int i = 0; i < (int)n; i++) { if (match_l[i] == -1) flow += find_min_dist_augment_path(i); } if (flow == 0) break; } vector> ret; for (int i = 0; i < (int)n; i++) { if (match_l[i] >= 0) ret.emplace_back(i, match_l[i]); } return ret; } /* http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=3198 */ void erase_edge(int a, int b) { if (match_l[a] == b) { match_l[a] = -1; match_r[b] = -1; } g[a].erase(find(begin(g[a]), end(g[a]), b)); rg[b].erase(find(begin(rg[b]), end(rg[b]), a)); } /* http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=0334 */ vector> lex_max_matching() { if (!matched) max_matching(); for (auto& vs : g) sort(begin(vs), end(vs)); vector> es; for (int i = 0; i < (int)n; i++) { if (match_l[i] == -1 || alive[i] == 0) { continue; } match_r[match_l[i]] = -1; match_l[i] = -1; ++time_stamp; find_augment_path(i); alive[i] = 0; es.emplace_back(i, match_l[i]); } return es; } vector min_vertex_cover() { auto visited = find_residual_path(); vector ret; for (int i = 0; i < (int)(n + m); i++) { if (visited[i] ^ (i < (int)n)) { ret.emplace_back(i); } } return ret; } /* https://atcoder.jp/contests/utpc2013/tasks/utpc2013_11 */ vector lex_min_vertex_cover(const vector& ord) { assert(ord.size() == n + m); auto res = build_risidual_graph(); vector> r_res(n + m + 2); for (int i = 0; i < (int)(n + m + 2); i++) { for (auto& j : res[i]) r_res[j].emplace_back(i); } queue que; vector visited(n + m + 2, -1); auto expand_left = [&](int t) { if (visited[t] != -1) return; que.emplace(t); visited[t] = 1; while (!que.empty()) { int idx = que.front(); que.pop(); for (auto& to : r_res[idx]) { if (visited[to] != -1) continue; visited[to] = 1; que.emplace(to); } } }; auto expand_right = [&](int t) { if (visited[t] != -1) return; que.emplace(t); visited[t] = 0; while (!que.empty()) { int idx = que.front(); que.pop(); for (auto& to : res[idx]) { if (visited[to] != -1) continue; visited[to] = 0; que.emplace(to); } } }; expand_right(n + m); expand_left(n + m + 1); vector ret; for (auto& t : ord) { if (t < (int)n) { expand_left(t); if (visited[t] & 1) ret.emplace_back(t); } else { expand_right(t); if (~visited[t] & 1) ret.emplace_back(t); } } return ret; } vector max_independent_set() { auto visited = find_residual_path(); vector ret; for (int i = 0; i < (int)(n + m); i++) { if (visited[i] ^ (i >= (int)n)) { ret.emplace_back(i); } } return ret; } vector> min_edge_cover() { auto es = max_matching(); for (int i = 0; i < (int)n; i++) { if (match_l[i] >= 0) { continue; } if (g[i].empty()) { return {}; } es.emplace_back(i, g[i][0]); } for (int i = 0; i < (int)m; i++) { if (match_r[i] >= 0) { continue; } if (rg[i].empty()) { return {}; } es.emplace_back(rg[i][0], i); } return es; } // left: [0,n), right: [n,n+m), S: n+m, T: n+m+1 vector> build_risidual_graph() { if (!matched) max_matching(); const size_t S = n + m; const size_t T = n + m + 1; vector> ris(n + m + 2); for (int i = 0; i < (int)n; i++) { if (match_l[i] == -1) ris[S].emplace_back(i); else ris[i].emplace_back(S); } for (int i = 0; i < (int)m; i++) { if (match_r[i] == -1) ris[i + n].emplace_back(T); else ris[T].emplace_back(i + n); } for (int i = 0; i < (int)n; i++) { for (auto& j : g[i]) { if (match_l[i] == j) ris[j + n].emplace_back(i); else ris[i].emplace_back(j + n); } } return ris; } private: vector find_residual_path() { auto res = build_risidual_graph(); queue que; vector visited(n + m + 2); que.emplace(n + m); visited[n + m] = true; while (!que.empty()) { int idx = que.front(); que.pop(); for (auto& to : res[idx]) { if (visited[to]) continue; visited[to] = true; que.emplace(to); } } return visited; } void build_augment_path() { queue que; dist.assign(g.size(), -1); for (int i = 0; i < (int)n; i++) { if (match_l[i] == -1) { que.emplace(i); dist[i] = 0; } } while (!que.empty()) { int a = que.front(); que.pop(); for (auto& b : g[a]) { int c = match_r[b]; if (c >= 0 && dist[c] == -1) { dist[c] = dist[a] + 1; que.emplace(c); } } } } bool find_min_dist_augment_path(int a) { used[a] = time_stamp; for (auto& b : g[a]) { int c = match_r[b]; if (c < 0 || (used[c] != (int)time_stamp && dist[c] == dist[a] + 1 && find_min_dist_augment_path(c))) { match_r[b] = a; match_l[a] = b; return true; } } return false; } bool find_augment_path(int a) { used[a] = time_stamp; for (auto& b : g[a]) { int c = match_r[b]; if (c < 0 || (alive[c] == 1 && used[c] != (int)time_stamp && find_augment_path(c))) { match_r[b] = a; match_l[a] = b; return true; } } return false; } }; /** * @brief Eulerian Trail(オイラー路) * @docs docs/eulerian-trail.md */ template struct EulerianTrail { vector>> g; vector> es; int M; vector used_vertex, used_edge, deg; explicit EulerianTrail(int V) : g(V), M(0), used_vertex(V), deg(V) {} void add_edge(int a, int b) { es.emplace_back(a, b); g[a].emplace_back(b, M); if (directed) { deg[a]++; deg[b]--; } else { g[b].emplace_back(a, M); deg[a]++; deg[b]++; } M++; } pair get_edge(int idx) const { return es[idx]; } vector> enumerate_eulerian_trail() { if (directed) { for (auto& p : deg) if (p != 0) return {}; } else { for (auto& p : deg) if (p & 1) return {}; } used_edge.assign(M, 0); vector> ret; for (int i = 0; i < (int)g.size(); i++) { if (g[i].empty() || used_vertex[i]) continue; ret.emplace_back(go(i)); } return ret; } vector> enumerate_semi_eulerian_trail() { UnionFind uf(g.size()); for (auto& p : es) uf.unite(p.first, p.second); vector> group(g.size()); for (int i = 0; i < (int)g.size(); i++) group[uf.find(i)].emplace_back(i); vector> ret; used_edge.assign(M, 0); for (auto& vs : group) { if (vs.empty()) continue; int latte = -1, malta = -1; if (directed) { for (auto& p : vs) { if (abs(deg[p]) > 1) { return {}; } else if (deg[p] == 1) { if (latte >= 0) return {}; latte = p; } } } else { for (auto& p : vs) { if (deg[p] & 1) { if (latte == -1) latte = p; else if (malta == -1) malta = p; else return {}; } } } ret.emplace_back(go(latte == -1 ? vs.front() : latte)); if (ret.back().empty()) ret.pop_back(); } return ret; } vector go(int s) { stack> st; vector ord; st.emplace(s, -1); while (!st.empty()) { int idx = st.top().first; used_vertex[idx] = true; if (g[idx].empty()) { ord.emplace_back(st.top().second); st.pop(); } else { auto e = g[idx].back(); g[idx].pop_back(); if (used_edge[e.second]) continue; used_edge[e.second] = true; st.emplace(e); } } ord.pop_back(); reverse(ord.begin(), ord.end()); return ord; } }; /** * @brief Bipartite Graph Edge Coloring(二部グラフの辺彩色) * @docs docs/bipartite-graph-edge-coloring.md * @see https://ei1333.hateblo.jp/entry/2020/08/25/015955 */ struct BipariteGraphEdgeColoring { private: vector> ans; vector A, B; int L, R; struct RegularGraph { int k{}, n{}; vector A, B; }; RegularGraph g; static UnionFind contract(valarray& deg, int k) { using pi = pair; priority_queue, greater<>> que; for (int i = 0; i < (int)deg.size(); i++) { que.emplace(deg[i], i); } UnionFind uf(deg.size()); while (que.size() > 1) { auto p = que.top(); que.pop(); auto q = que.top(); que.pop(); if (p.first + q.first > k) continue; p.first += q.first; uf.unite(p.second, q.second); que.emplace(p); } return uf; } RegularGraph build_k_regular_graph() { valarray deg[2]; deg[0] = valarray(L); deg[1] = valarray(R); for (auto& p : A) deg[0][p]++; for (auto& p : B) deg[1][p]++; int k = max(deg[0].max(), deg[1].max()); /* step 1 */ UnionFind uf[2]; uf[0] = contract(deg[0], k); uf[1] = contract(deg[1], k); vector id[2]; int ptr[] = {0, 0}; id[0] = vector(L); id[1] = vector(R); for (int i = 0; i < L; i++) if (uf[0].find(i) == i) id[0][i] = ptr[0]++; for (int i = 0; i < R; i++) if (uf[1].find(i) == i) id[1][i] = ptr[1]++; /* step 2 */ int N = max(ptr[0], ptr[1]); deg[0] = valarray(N); deg[1] = valarray(N); /* step 3 */ vector C, D; C.reserve(N * k); D.reserve(N * k); for (int i = 0; i < (int)A.size(); i++) { int u = id[0][uf[0].find(A[i])]; int v = id[1][uf[1].find(B[i])]; C.emplace_back(u); D.emplace_back(v); deg[0][u]++; deg[1][v]++; } int j = 0; for (int i = 0; i < N; i++) { while (deg[0][i] < k) { while (deg[1][j] == k) ++j; C.emplace_back(i); D.emplace_back(j); ++deg[0][i]; ++deg[1][j]; } } return {k, N, C, D}; } void rec(const vector& ord, int k) { if (k == 0) { return; } else if (k == 1) { ans.emplace_back(ord); return; } else if ((k & 1) == 0) { EulerianTrail et(g.n + g.n); for (auto& p : ord) et.add_edge(g.A[p], g.B[p] + g.n); auto paths = et.enumerate_eulerian_trail(); vector path; for (auto& ps : paths) { for (auto& e : ps) path.emplace_back(ord[e]); } vector beet[2]; for (int i = 0; i < (int)path.size(); i++) { beet[i & 1].emplace_back(path[i]); } rec(beet[0], k / 2); rec(beet[1], k / 2); } else { BipartiteFlow flow(g.n, g.n); for (auto& i : ord) flow.add_edge(g.A[i], g.B[i]); flow.max_matching(); vector beet; ans.emplace_back(); for (auto& i : ord) { if (flow.match_l[g.A[i]] == g.B[i]) { flow.match_l[g.A[i]] = -1; ans.back().emplace_back(i); } else { beet.emplace_back(i); } } rec(beet, k - 1); } } public: explicit BipariteGraphEdgeColoring() : L(0), R(0) {} void add_edge(int a, int b) { A.emplace_back(a); B.emplace_back(b); L = max(L, a + 1); R = max(R, b + 1); } vector> build() { g = build_k_regular_graph(); vector ord(g.A.size()); iota(ord.begin(), ord.end(), 0); rec(ord, g.k); vector> res; for (int i = 0; i < (int)ans.size(); i++) { res.emplace_back(); for (auto& j : ans[i]) if (j < (int)A.size()) res.back().emplace_back(j); } return res; } }; int main() { const auto [N, M] = in.tup(); const auto Ass = in.vvec(N, N); Vec lds(N,0), rds(N, 0); Vec> es; for (int i : rep(N)) { for (int j : rep(N)) { lds[i] += Ass[i][j]; rds[j] += Ass[i][j]; } } for (int i : rep(N)) { if (lds[i] != M) { return out.ln(-1); } if (rds[i] != M) { return out.ln(-1); } } BipariteGraphEdgeColoring g; for (int i : rep(N)) { for (int j : rep(N)) { for (auto _temp_name_3 [[maybe_unused]] : rep(Ass[i][j])) { g.add_edge(i, j); es.push_back({i, j}); } } } const auto vss = g.build(); for (const auto& vs : vss) { Vec Ps(N, -1); for (int ei : vs) { const auto [i, j] = es[ei]; Ps[i] = j; } plusAll(Ps, 1); out.ln(Ps); } return 0; }