#line 1 "/home/maspy/compro/library/my_template.hpp" #if defined(LOCAL) #include #else #pragma GCC optimize("Ofast") #pragma GCC optimize("unroll-loops") #include using namespace std; using ll = long long; using u32 = unsigned int; using u64 = unsigned long long; using i128 = __int128; using u128 = unsigned __int128; using f128 = __float128; template constexpr T infty = 0; template <> constexpr int infty = 1'000'000'000; template <> constexpr ll infty = ll(infty) * infty * 2; template <> constexpr u32 infty = infty; template <> constexpr u64 infty = infty; template <> constexpr i128 infty = i128(infty) * infty; template <> constexpr double infty = infty; template <> constexpr long double infty = infty; using pi = pair; using vi = vector; template using vc = vector; template using vvc = vector>; template using vvvc = vector>; template using vvvvc = vector>; template using vvvvvc = vector>; template using pq = priority_queue; template using pqg = priority_queue, greater>; #define vv(type, name, h, ...) \ vector> name(h, vector(__VA_ARGS__)) #define vvv(type, name, h, w, ...) \ vector>> name( \ h, vector>(w, vector(__VA_ARGS__))) #define vvvv(type, name, a, b, c, ...) \ vector>>> name( \ a, vector>>( \ b, vector>(c, vector(__VA_ARGS__)))) // https://trap.jp/post/1224/ #define FOR1(a) for (ll _ = 0; _ < ll(a); ++_) #define FOR2(i, a) for (ll i = 0; i < ll(a); ++i) #define FOR3(i, a, b) for (ll i = a; i < ll(b); ++i) #define FOR4(i, a, b, c) for (ll i = a; i < ll(b); i += (c)) #define FOR1_R(a) for (ll i = (a)-1; i >= ll(0); --i) #define FOR2_R(i, a) for (ll i = (a)-1; i >= ll(0); --i) #define FOR3_R(i, a, b) for (ll i = (b)-1; i >= ll(a); --i) #define overload4(a, b, c, d, e, ...) e #define overload3(a, b, c, d, ...) d #define FOR(...) overload4(__VA_ARGS__, FOR4, FOR3, FOR2, FOR1)(__VA_ARGS__) #define FOR_R(...) overload3(__VA_ARGS__, FOR3_R, FOR2_R, FOR1_R)(__VA_ARGS__) #define FOR_subset(t, s) \ for (ll t = (s); t >= 0; t = (t == 0 ? -1 : (t - 1) & (s))) #define all(x) x.begin(), x.end() #define len(x) ll(x.size()) #define elif else if #define eb emplace_back #define mp make_pair #define mt make_tuple #define fi first #define se second #define stoi stoll int popcnt(int x) { return __builtin_popcount(x); } int popcnt(u32 x) { return __builtin_popcount(x); } int popcnt(ll x) { return __builtin_popcountll(x); } int popcnt(u64 x) { return __builtin_popcountll(x); } int popcnt_mod_2(int x) { return __builtin_parity(x); } int popcnt_mod_2(u32 x) { return __builtin_parity(x); } int popcnt_mod_2(ll x) { return __builtin_parityll(x); } int popcnt_mod_2(u64 x) { return __builtin_parityll(x); } // (0, 1, 2, 3, 4) -> (-1, 0, 1, 1, 2) int topbit(int x) { return (x == 0 ? -1 : 31 - __builtin_clz(x)); } int topbit(u32 x) { return (x == 0 ? -1 : 31 - __builtin_clz(x)); } int topbit(ll x) { return (x == 0 ? -1 : 63 - __builtin_clzll(x)); } int topbit(u64 x) { return (x == 0 ? -1 : 63 - __builtin_clzll(x)); } // (0, 1, 2, 3, 4) -> (-1, 0, 1, 0, 2) int lowbit(int x) { return (x == 0 ? -1 : __builtin_ctz(x)); } int lowbit(u32 x) { return (x == 0 ? -1 : __builtin_ctz(x)); } int lowbit(ll x) { return (x == 0 ? -1 : __builtin_ctzll(x)); } int lowbit(u64 x) { return (x == 0 ? -1 : __builtin_ctzll(x)); } template T floor(T a, T b) { return a / b - (a % b && (a ^ b) < 0); } template T ceil(T x, T y) { return floor(x + y - 1, y); } template T bmod(T x, T y) { return x - y * floor(x, y); } template pair divmod(T x, T y) { T q = floor(x, y); return {q, x - q * y}; } template T SUM(const vector &A) { T sm = 0; for (auto &&a: A) sm += a; return sm; } #define MIN(v) *min_element(all(v)) #define MAX(v) *max_element(all(v)) #define LB(c, x) distance((c).begin(), lower_bound(all(c), (x))) #define UB(c, x) distance((c).begin(), upper_bound(all(c), (x))) #define UNIQUE(x) \ sort(all(x)), x.erase(unique(all(x)), x.end()), x.shrink_to_fit() template T POP(deque &que) { T a = que.front(); que.pop_front(); return a; } template T POP(pq &que) { T a = que.top(); que.pop(); return a; } template T POP(pqg &que) { T a = que.top(); que.pop(); return a; } template T POP(vc &que) { T a = que.back(); que.pop_back(); return a; } template ll binary_search(F check, ll ok, ll ng, bool check_ok = true) { if (check_ok) assert(check(ok)); while (abs(ok - ng) > 1) { auto x = (ng + ok) / 2; (check(x) ? ok : ng) = x; } return ok; } template double binary_search_real(F check, double ok, double ng, int iter = 100) { FOR(iter) { double x = (ok + ng) / 2; (check(x) ? ok : ng) = x; } return (ok + ng) / 2; } template inline bool chmax(T &a, const S &b) { return (a < b ? a = b, 1 : 0); } template inline bool chmin(T &a, const S &b) { return (a > b ? a = b, 1 : 0); } // ? は -1 vc s_to_vi(const string &S, char first_char) { vc A(S.size()); FOR(i, S.size()) { A[i] = (S[i] != '?' ? S[i] - first_char : -1); } return A; } template vector cumsum(vector &A, int off = 1) { int N = A.size(); vector B(N + 1); FOR(i, N) { B[i + 1] = B[i] + A[i]; } if (off == 0) B.erase(B.begin()); return B; } // stable sort template vector argsort(const vector &A) { vector ids(len(A)); iota(all(ids), 0); sort(all(ids), [&](int i, int j) { return (A[i] == A[j] ? i < j : A[i] < A[j]); }); return ids; } // A[I[0]], A[I[1]], ... template vc rearrange(const vc &A, const vc &I) { vc B(len(I)); FOR(i, len(I)) B[i] = A[I[i]]; return B; } #endif #line 1 "/home/maspy/compro/library/other/io.hpp" #define FASTIO #include // https://judge.yosupo.jp/submission/21623 namespace fastio { static constexpr uint32_t SZ = 1 << 17; char ibuf[SZ]; char obuf[SZ]; char out[100]; // pointer of ibuf, obuf uint32_t pil = 0, pir = 0, por = 0; struct Pre { char num[10000][4]; constexpr Pre() : num() { for (int i = 0; i < 10000; i++) { int n = i; for (int j = 3; j >= 0; j--) { num[i][j] = n % 10 | '0'; n /= 10; } } } } constexpr pre; inline void load() { memcpy(ibuf, ibuf + pil, pir - pil); pir = pir - pil + fread(ibuf + pir - pil, 1, SZ - pir + pil, stdin); pil = 0; if (pir < SZ) ibuf[pir++] = '\n'; } inline void flush() { fwrite(obuf, 1, por, stdout); por = 0; } void rd(char &c) { do { if (pil + 1 > pir) load(); c = ibuf[pil++]; } while (isspace(c)); } void rd(string &x) { x.clear(); char c; do { if (pil + 1 > pir) load(); c = ibuf[pil++]; } while (isspace(c)); do { x += c; if (pil == pir) load(); c = ibuf[pil++]; } while (!isspace(c)); } template void rd_real(T &x) { string s; rd(s); x = stod(s); } template void rd_integer(T &x) { if (pil + 100 > pir) load(); char c; do c = ibuf[pil++]; while (c < '-'); bool minus = 0; if constexpr (is_signed::value || is_same_v) { if (c == '-') { minus = 1, c = ibuf[pil++]; } } x = 0; while ('0' <= c) { x = x * 10 + (c & 15), c = ibuf[pil++]; } if constexpr (is_signed::value || is_same_v) { if (minus) x = -x; } } void rd(int &x) { rd_integer(x); } void rd(ll &x) { rd_integer(x); } void rd(i128 &x) { rd_integer(x); } void rd(u32 &x) { rd_integer(x); } void rd(u64 &x) { rd_integer(x); } void rd(u128 &x) { rd_integer(x); } void rd(double &x) { rd_real(x); } void rd(long double &x) { rd_real(x); } void rd(f128 &x) { rd_real(x); } template void rd(pair &p) { return rd(p.first), rd(p.second); } template void rd_tuple(T &t) { if constexpr (N < std::tuple_size::value) { auto &x = std::get(t); rd(x); rd_tuple(t); } } template void rd(tuple &tpl) { rd_tuple(tpl); } template void rd(array &x) { for (auto &d: x) rd(d); } template void rd(vc &x) { for (auto &d: x) rd(d); } void read() {} template void read(H &h, T &... t) { rd(h), read(t...); } void wt(const char c) { if (por == SZ) flush(); obuf[por++] = c; } void wt(const string s) { for (char c: s) wt(c); } void wt(const char *s) { size_t len = strlen(s); for (size_t i = 0; i < len; i++) wt(s[i]); } template void wt_integer(T x) { if (por > SZ - 100) flush(); if (x < 0) { obuf[por++] = '-', x = -x; } int outi; for (outi = 96; x >= 10000; outi -= 4) { memcpy(out + outi, pre.num[x % 10000], 4); x /= 10000; } if (x >= 1000) { memcpy(obuf + por, pre.num[x], 4); por += 4; } else if (x >= 100) { memcpy(obuf + por, pre.num[x] + 1, 3); por += 3; } else if (x >= 10) { int q = (x * 103) >> 10; obuf[por] = q | '0'; obuf[por + 1] = (x - q * 10) | '0'; por += 2; } else obuf[por++] = x | '0'; memcpy(obuf + por, out + outi + 4, 96 - outi); por += 96 - outi; } template void wt_real(T x) { ostringstream oss; oss << fixed << setprecision(15) << double(x); string s = oss.str(); wt(s); } void wt(int x) { wt_integer(x); } void wt(ll x) { wt_integer(x); } void wt(i128 x) { wt_integer(x); } void wt(u32 x) { wt_integer(x); } void wt(u64 x) { wt_integer(x); } void wt(u128 x) { wt_integer(x); } void wt(double x) { wt_real(x); } void wt(long double x) { wt_real(x); } void wt(f128 x) { wt_real(x); } template void wt(const pair val) { wt(val.first); wt(' '); wt(val.second); } template void wt_tuple(const T t) { if constexpr (N < std::tuple_size::value) { if constexpr (N > 0) { wt(' '); } const auto x = std::get(t); wt(x); wt_tuple(t); } } template void wt(tuple tpl) { wt_tuple(tpl); } template void wt(const array val) { auto n = val.size(); for (size_t i = 0; i < n; i++) { if (i) wt(' '); wt(val[i]); } } template void wt(const vector val) { auto n = val.size(); for (size_t i = 0; i < n; i++) { if (i) wt(' '); wt(val[i]); } } void print() { wt('\n'); } template void print(Head &&head, Tail &&... tail) { wt(head); if (sizeof...(Tail)) wt(' '); print(forward(tail)...); } // gcc expansion. called automaticall after main. void __attribute__((destructor)) _d() { flush(); } } // namespace fastio using fastio::read; using fastio::print; using fastio::flush; #define INT(...) \ int __VA_ARGS__; \ read(__VA_ARGS__) #define LL(...) \ ll __VA_ARGS__; \ read(__VA_ARGS__) #define U32(...) \ u32 __VA_ARGS__; \ read(__VA_ARGS__) #define U64(...) \ u64 __VA_ARGS__; \ read(__VA_ARGS__) #define STR(...) \ string __VA_ARGS__; \ read(__VA_ARGS__) #define CHAR(...) \ char __VA_ARGS__; \ read(__VA_ARGS__) #define DBL(...) \ double __VA_ARGS__; \ read(__VA_ARGS__) #define VEC(type, name, size) \ vector name(size); \ read(name) #define VV(type, name, h, w) \ vector> name(h, vector(w)); \ read(name) void YES(bool t = 1) { print(t ? "YES" : "NO"); } void NO(bool t = 1) { YES(!t); } void Yes(bool t = 1) { print(t ? "Yes" : "No"); } void No(bool t = 1) { Yes(!t); } void yes(bool t = 1) { print(t ? "yes" : "no"); } void no(bool t = 1) { yes(!t); } #line 3 "main.cpp" #line 2 "/home/maspy/compro/library/ds/segtree/segtree.hpp" template struct SegTree { using MX = Monoid; using X = typename MX::value_type; using value_type = X; vc dat; int n, log, size; SegTree() {} SegTree(int n) { build(n); } template SegTree(int n, F f) { build(n, f); } SegTree(const vc& v) { build(v); } void build(int m) { build(m, [](int i) -> X { return MX::unit(); }); } void build(const vc& v) { build(len(v), [&](int i) -> X { return v[i]; }); } template void build(int m, F f) { n = m, log = 1; while ((1 << log) < n) ++log; size = 1 << log; dat.assign(size << 1, MX::unit()); FOR(i, n) dat[size + i] = f(i); FOR_R(i, 1, size) update(i); } X get(int i) { return dat[size + i]; } vc get_all() { return {dat.begin() + size, dat.begin() + size + n}; } void update(int i) { dat[i] = Monoid::op(dat[2 * i], dat[2 * i + 1]); } void set(int i, const X& x) { assert(i < n); dat[i += size] = x; while (i >>= 1) update(i); } void multiply(int i, const X& x) { assert(i < n); i += size; dat[i] = Monoid::op(dat[i], x); while (i >>= 1) update(i); } X prod(int L, int R) { assert(0 <= L && L <= R && R <= n); X vl = Monoid::unit(), vr = Monoid::unit(); L += size, R += size; while (L < R) { if (L & 1) vl = Monoid::op(vl, dat[L++]); if (R & 1) vr = Monoid::op(dat[--R], vr); L >>= 1, R >>= 1; } return Monoid::op(vl, vr); } X prod_all() { return dat[1]; } template int max_right(F check, int L) { assert(0 <= L && L <= n && check(Monoid::unit())); if (L == n) return n; L += size; X sm = Monoid::unit(); do { while (L % 2 == 0) L >>= 1; if (!check(Monoid::op(sm, dat[L]))) { while (L < size) { L = 2 * L; if (check(Monoid::op(sm, dat[L]))) { sm = Monoid::op(sm, dat[L++]); } } return L - size; } sm = Monoid::op(sm, dat[L++]); } while ((L & -L) != L); return n; } template int min_left(F check, int R) { assert(0 <= R && R <= n && check(Monoid::unit())); if (R == 0) return 0; R += size; X sm = Monoid::unit(); do { --R; while (R > 1 && (R % 2)) R >>= 1; if (!check(Monoid::op(dat[R], sm))) { while (R < size) { R = 2 * R + 1; if (check(Monoid::op(dat[R], sm))) { sm = Monoid::op(dat[R--], sm); } } return R + 1 - size; } sm = Monoid::op(dat[R], sm); } while ((R & -R) != R); return 0; } // prod_{l<=i= r) break; if (l & 1) { x = Monoid::op(x, dat[(size >> k) + ((l++) ^ xor_val)]); } if (r & 1) { x = Monoid::op(x, dat[(size >> k) + ((--r) ^ xor_val)]); } l /= 2, r /= 2, xor_val /= 2; } return x; } }; #line 1 "/home/maspy/compro/library/ds/fastset.hpp" // 64-ary tree // space: (N/63) * u64 struct FastSet { static constexpr u32 B = 64; int n, log; vvc seg; FastSet() {} FastSet(int n) { build(n); } template FastSet(int n, F f) { build(n, f); } void build(int m) { seg.clear(); n = m; do { seg.push_back(vc((m + B - 1) / B)); m = (m + B - 1) / B; } while (m > 1); log = len(seg); } template void build(int n, F f) { build(n); FOR(i, n) { seg[0][i / B] |= u64(f(i)) << (i % B); } FOR(h, log - 1) { FOR(i, len(seg[h])) { seg[h + 1][i / B] |= u64(bool(seg[h][i])) << (i % B); } } } bool operator[](int i) const { return seg[0][i / B] >> (i % B) & 1; } void insert(int i) { for (int h = 0; h < log; h++) { seg[h][i / B] |= u64(1) << (i % B), i /= B; } } void add(int i) { insert(i); } void erase(int i) { u64 x = 0; for (int h = 0; h < log; h++) { seg[h][i / B] &= ~(u64(1) << (i % B)); seg[h][i / B] |= x << (i % B); x = bool(seg[h][i / B]); i /= B; } } void remove(int i) { erase(i); } // min[x,n) or n int next(int i) { assert(i <= n); chmax(i, 0); for (int h = 0; h < log; h++) { if (i / B == seg[h].size()) break; u64 d = seg[h][i / B] >> (i % B); if (!d) { i = i / B + 1; continue; } i += lowbit(d); for (int g = h - 1; g >= 0; g--) { i *= B; i += lowbit(seg[g][i / B]); } return i; } return n; } // max [0,x], or -1 int prev(int i) { assert(i >= -1); if (i >= n) i = n - 1; for (int h = 0; h < log; h++) { if (i == -1) break; u64 d = seg[h][i / B] << (63 - i % B); if (!d) { i = i / B - 1; continue; } i -= __builtin_clzll(d); for (int g = h - 1; g >= 0; g--) { i *= B; i += topbit(seg[g][i / B]); } return i; } return -1; } // [l, r) template void enumerate(int l, int r, F f) { for (int x = next(l); x < r; x = next(x + 1)) f(x); } string to_string() { string s(n, '?'); for (int i = 0; i < n; ++i) s[i] = ((*this)[i] ? '1' : '0'); return s; } }; #line 6 "main.cpp" /* A[0],...,A[i] のうちひとつが手元にある A[1+i] を追加 どれかを置く - A[1+i] を手元に残せるか? - 手元のうちでその時点でのランクが偶数のものがあるか - 手元にある x をキープできるか - x をキープしても A[1+i] が偶数番目かどうか - prefix, suffix どちらかが無理になる - rank even で残せないものの個数 / 残せるものの個数 - rank odd で残せないものの個数 / 残せるものの個数 */ using Data = array, 2>; struct Mono { using value_type = Data; using X = value_type; static X op(X x, X y) { int left = x[0][0] + x[0][1] + x[1][0] + x[1][1]; FOR(i, 2) FOR(j, 2) { int k = (i + left) % 2; x[k][j] += y[i][j]; } return x; } static constexpr X unit() { return {0, 0, 0, 0}; } static constexpr bool commute = 0; }; void solve() { INT(N); VEC(int, A, N); for (auto& x: A) --x; { vc pos(N); FOR(i, N) pos[A[i]] = i; A = pos; } auto to_seg = [&](bool can) -> Data { if (can) return {0, 1, 0, 0}; return {1, 0, 0, 0}; }; SegTree seg(N); // A[0] だけ残せるところから始める FastSet ss(N); ss.insert(A[0]); seg.set(A[0], to_seg(true)); FOR(i, 1, N) { int x = A[i]; auto L = seg.prod(0, x); auto ALL = seg.prod_all(); // x を残せるか bool can = (ALL[0][1] > 0); // x を使う場合に手元に残るのは? bool pref = 0; pref = (L[0][0] + L[0][1] + L[1][0] + L[1][1]) % 2 == 1; if (pref) { // suffix の要素は残せなくなる ss.enumerate(x, N, [&](int i) -> void { ss.erase(i); seg.set(i, to_seg(false)); }); } else { ss.enumerate(0, x, [&](int i) -> void { ss.erase(i); seg.set(i, to_seg(false)); }); } seg.set(x, to_seg(can)); if (can) ss.insert(x); } bool ok = false; ss.enumerate(0, N, [&](int x) -> void { if (x % 2 == 0) ok = true; }); // ああ構築 if (!ok) return No(); assert(0); } signed main() { int T = 1; // INT(T); FOR(T) solve(); return 0; }