#include // #include using namespace std; using namespace numbers; using uint = unsigned int; template struct modular_fixed_base{ static constexpr uint mod(){ return _mod; } template static vector precalc_power(T base, int SZ){ vector res(SZ + 1, 1); for(auto i = 1; i <= SZ; ++ i) res[i] = res[i - 1] * base; return res; } static vector _INV; static void precalc_inverse(int SZ){ if(_INV.empty()) _INV.assign(2, 1); for(auto x = _INV.size(); x <= SZ; ++ x) _INV.push_back(_mod / x * -_INV[_mod % x]); } // _mod must be a prime static modular_fixed_base _primitive_root; static modular_fixed_base primitive_root(){ if(_primitive_root) return _primitive_root; if(_mod == 2) return _primitive_root = 1; if(_mod == 998244353) return _primitive_root = 3; uint divs[20] = {}; divs[0] = 2; int cnt = 1; uint x = (_mod - 1) / 2; while(x % 2 == 0) x /= 2; for(auto i = 3; 1LL * 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(auto g = 2; ; ++ g){ bool ok = true; for(auto i = 0; i < cnt; ++ i){ if((modular_fixed_base(g).power((_mod - 1) / divs[i])) == 1){ ok = false; break; } } if(ok) return _primitive_root = g; } } constexpr modular_fixed_base(): data(){ } modular_fixed_base(const double &x){ data = normalize(llround(x)); } modular_fixed_base(const long double &x){ data = normalize(llround(x)); } template::value>::type* = nullptr> modular_fixed_base(const T &x){ data = normalize(x); } template::value>::type* = nullptr> static uint normalize(const T &x){ int sign = x >= 0 ? 1 : -1; uint v = _mod <= sign * x ? sign * x % _mod : sign * x; if(sign == -1 && v) v = _mod - v; return v; } const uint &operator()() const{ return data; } template operator T() const{ return data; } modular_fixed_base &operator+=(const modular_fixed_base &otr){ if((data += otr.data) >= _mod) data -= _mod; return *this; } modular_fixed_base &operator-=(const modular_fixed_base &otr){ if((data += _mod - otr.data) >= _mod) data -= _mod; return *this; } template::value>::type* = nullptr> modular_fixed_base &operator+=(const T &otr){ return *this += modular_fixed_base(otr); } template::value>::type* = nullptr> modular_fixed_base &operator-=(const T &otr){ return *this -= modular_fixed_base(otr); } modular_fixed_base &operator++(){ return *this += 1; } modular_fixed_base &operator--(){ return *this += _mod - 1; } modular_fixed_base operator++(int){ modular_fixed_base result(*this); *this += 1; return result; } modular_fixed_base operator--(int){ modular_fixed_base result(*this); *this += _mod - 1; return result; } modular_fixed_base operator-() const{ return modular_fixed_base(_mod - data); } modular_fixed_base &operator*=(const modular_fixed_base &rhs){ data = (unsigned long long)data * rhs.data % _mod; return *this; } template::value>::type* = nullptr> modular_fixed_base &inplace_power(T e){ if(!data) return *this = {}; if(data == 1) return *this; if(data == mod() - 1) return e % 2 ? *this : *this = -*this; if(e < 0) *this = 1 / *this, e = -e; modular_fixed_base res = 1; for(; e; *this *= *this, e >>= 1) if(e & 1) res *= *this; return *this = res; } template::value>::type* = nullptr> modular_fixed_base power(T e) const{ return modular_fixed_base(*this).inplace_power(e); } modular_fixed_base &operator/=(const modular_fixed_base &otr){ int a = otr.data, m = _mod, u = 0, v = 1; if(a < _INV.size()) return *this *= _INV[a]; while(a){ int t = m / a; m -= t * a; swap(a, m); u -= t * v; swap(u, v); } assert(m == 1); return *this *= u; } uint data; }; template vector> modular_fixed_base<_mod>::_INV; template modular_fixed_base<_mod> modular_fixed_base<_mod>::_primitive_root; template bool operator==(const modular_fixed_base<_mod> &lhs, const modular_fixed_base<_mod> &rhs){ return lhs.data == rhs.data; } template::value>::type* = nullptr> bool operator==(const modular_fixed_base<_mod> &lhs, T rhs){ return lhs == modular_fixed_base<_mod>(rhs); } template::value>::type* = nullptr> bool operator==(T lhs, const modular_fixed_base<_mod> &rhs){ return modular_fixed_base<_mod>(lhs) == rhs; } template bool operator!=(const modular_fixed_base<_mod> &lhs, const modular_fixed_base<_mod> &rhs){ return !(lhs == rhs); } template::value>::type* = nullptr> bool operator!=(const modular_fixed_base<_mod> &lhs, T rhs){ return !(lhs == rhs); } template::value>::type* = nullptr> bool operator!=(T lhs, const modular_fixed_base<_mod> &rhs){ return !(lhs == rhs); } template bool operator<(const modular_fixed_base<_mod> &lhs, const modular_fixed_base<_mod> &rhs){ return lhs.data < rhs.data; } template bool operator>(const modular_fixed_base<_mod> &lhs, const modular_fixed_base<_mod> &rhs){ return lhs.data > rhs.data; } template bool operator<=(const modular_fixed_base<_mod> &lhs, const modular_fixed_base<_mod> &rhs){ return lhs.data <= rhs.data; } template bool operator>=(const modular_fixed_base<_mod> &lhs, const modular_fixed_base<_mod> &rhs){ return lhs.data >= rhs.data; } template modular_fixed_base<_mod> operator+(const modular_fixed_base<_mod> &lhs, const modular_fixed_base<_mod> &rhs){ return modular_fixed_base<_mod>(lhs) += rhs; } template::value>::type* = nullptr> modular_fixed_base<_mod> operator+(const modular_fixed_base<_mod> &lhs, T rhs){ return modular_fixed_base<_mod>(lhs) += rhs; } template::value>::type* = nullptr> modular_fixed_base<_mod> operator+(T lhs, const modular_fixed_base<_mod> &rhs){ return modular_fixed_base<_mod>(lhs) += rhs; } template modular_fixed_base<_mod> operator-(const modular_fixed_base<_mod> &lhs, const modular_fixed_base<_mod> &rhs){ return modular_fixed_base<_mod>(lhs) -= rhs; } template::value>::type* = nullptr> modular_fixed_base<_mod> operator-(const modular_fixed_base<_mod> &lhs, T rhs){ return modular_fixed_base<_mod>(lhs) -= rhs; } template::value>::type* = nullptr> modular_fixed_base<_mod> operator-(T lhs, const modular_fixed_base<_mod> &rhs){ return modular_fixed_base<_mod>(lhs) -= rhs; } template modular_fixed_base<_mod> operator*(const modular_fixed_base<_mod> &lhs, const modular_fixed_base<_mod> &rhs){ return modular_fixed_base<_mod>(lhs) *= rhs; } template::value>::type* = nullptr> modular_fixed_base<_mod> operator*(const modular_fixed_base<_mod> &lhs, T rhs){ return modular_fixed_base<_mod>(lhs) *= rhs; } template::value>::type* = nullptr> modular_fixed_base<_mod> operator*(T lhs, const modular_fixed_base<_mod> &rhs){ return modular_fixed_base<_mod>(lhs) *= rhs; } template modular_fixed_base<_mod> operator/(const modular_fixed_base<_mod> &lhs, const modular_fixed_base<_mod> &rhs) { return modular_fixed_base<_mod>(lhs) /= rhs; } template::value>::type* = nullptr> modular_fixed_base<_mod> operator/(const modular_fixed_base<_mod> &lhs, T rhs) { return modular_fixed_base<_mod>(lhs) /= rhs; } template::value>::type* = nullptr> modular_fixed_base<_mod> operator/(T lhs, const modular_fixed_base<_mod> &rhs) { return modular_fixed_base<_mod>(lhs) /= rhs; } template istream &operator>>(istream &in, modular_fixed_base<_mod> &number){ long long x; in >> x; number.data = modular_fixed_base<_mod>::normalize(x); return in; } // #define _SHOW_FRACTION template ostream &operator<<(ostream &out, const modular_fixed_base<_mod> &number){ out << number(); #if defined(LOCAL) && defined(_SHOW_FRACTION) cerr << "("; for(auto d = 1; ; ++ d){ if((number * d).data <= 1000000){ cerr << (number * d).data; if(d != 1) cerr << "/" << d; break; } else if((-number * d).data <= 1000000){ cerr << "-" << (-number * d).data; if(d != 1) cerr << "/" << d; break; } } cerr << ")"; #endif return out; } #undef _SHOW_FRACTION // const uint mod = 1e9 + 7; // 1000000007 const uint mod = (119 << 23) + 1; // 998244353 // const uint mod = 1e9 + 9; // 1000000009 using modular = modular_fixed_base; template struct combinatorics{ // O(n) static vector precalc_fact(int n){ vector f(n + 1, 1); for(auto i = 1; i <= n; ++ i) f[i] = f[i - 1] * i; return f; } // O(n * m) static vector> precalc_C(int n, int m){ vector> c(n + 1, vector(m + 1)); for(auto i = 0; i <= n; ++ i) for(auto j = 0; j <= min(i, m); ++ j) c[i][j] = i && j ? c[i - 1][j - 1] + c[i - 1][j] : T(1); return c; } int SZ = 0; vector inv, fact, invfact; combinatorics(){ } // O(SZ) combinatorics(int SZ): SZ(SZ), inv(SZ + 1, 1), fact(SZ + 1, 1), invfact(SZ + 1, 1){ for(auto i = 1; i <= SZ; ++ i) fact[i] = fact[i - 1] * i; invfact[SZ] = 1 / fact[SZ]; for(auto i = SZ - 1; i >= 0; -- i){ invfact[i] = invfact[i + 1] * (i + 1); inv[i + 1] = invfact[i + 1] * fact[i]; } } // O(1) T C(int n, int k) const{ return n < 0 ? C(-n + k - 1, k) * (k & 1 ? -1 : 1) : n < k || k < 0 ? T() : fact[n] * invfact[k] * invfact[n - k]; } // O(1) T P(int n, int k) const{ return n < k ? T() : fact[n] * invfact[n - k]; } // O(1) T H(int n, int k) const{ return C(n + k - 1, k); } // O(min(k, n - k)) T naive_C(long long n, long long k) const{ if(n < k) return 0; T res = 1; k = min(k, n - k); for(auto i = n; i > n - k; -- i) res *= i; return res * invfact[k]; } // O(k) T naive_P(long long n, int k) const{ if(n < k) return 0; T res = 1; for(auto i = n; i > n - k; -- i) res *= i; return res; } // O(k) T naive_H(long long n, int k) const{ return naive_C(n + k - 1, k); } // O(1) bool parity_C(long long n, long long k) const{ return n < k ? false : (n & k) == k; } // Number of ways to place n '('s and k ')'s starting with m copies of '(' such that in each prefix, number of '(' is equal or greater than ')' // Catalan(n, n, 0): n-th catalan number // Catalan(s, s+k-1, k-1): sum of products of k catalan numbers where the index of product sums up to s. // O(1) T Catalan(int n, int k, int m = 0) const{ assert(0 <= min({n, k, m})); return k <= m ? C(n + k, n) : k <= n + m ? C(n + k, n) - C(n + k, k - m - 1) : T(); } }; // T must be of modular type // mod must be a prime // Requires modular template struct number_theoric_transform_wrapper{ // i \in [2^k, 2^{k+1}) holds w_{2^k+1}^{i-2^k} static vector root, buffer1, buffer2; static void adjust_root(int n){ if(root.empty()) root = {1, 1}; for(auto k = (int)root.size(); k < n; k <<= 1){ root.resize(n, 1); T w = T::primitive_root().power((T::mod() - 1) / (k << 1)); for(auto i = k; i < k << 1; ++ i) root[i] = i & 1 ? root[i >> 1] * w : root[i >> 1]; } } // n must be a power of two // p must have next n memories allocated // O(n * log(n)) static void transform(int n, T *p, bool invert = false){ assert(n && __builtin_popcount(n) == 1 && (T::mod() - 1) % n == 0); for(auto i = 1, j = 0; i < n; ++ i){ int bit = n >> 1; for(; j & bit; bit >>= 1) j ^= bit; j ^= bit; if(i < j) swap(p[i], p[j]); } adjust_root(n); for(auto len = 1; len < n; len <<= 1) for(auto i = 0; i < n; i += len << 1) for(auto j = 0; j < len; ++ j){ T x = p[i + j], y = p[len + i + j] * root[len + j]; p[i + j] = x + y, p[len + i + j] = x - y; } if(invert){ reverse(p + 1, p + n); T inv_n = T(1) / n; for(auto i = 0; i < n; ++ i) p[i] *= inv_n; } } static void transform(vector &p, bool invert = false){ transform((int)p.size(), p.data(), invert); } // Double the length of the ntt array // n must be a power of two // p must have next 2n memories allocated // O(n * log(n)) static void double_up(int n, T *p){ assert(n && __builtin_popcount(n) == 1 && (T().mod() - 1) % (n << 1) == 0); buffer1.resize(n << 1); for(auto i = 0; i < n; ++ i) buffer1[i << 1] = p[i]; transform(n, p, true); adjust_root(n << 1); for(auto i = 0; i < n; ++ i) p[i] *= root[n | i]; transform(n, p); for(auto i = 0; i < n; ++ i) buffer1[i << 1 | 1] = p[i]; copy(buffer1.begin(), buffer1.begin() + 2 * n, p); } static void double_up(vector &p){ int n = (int)p.size(); p.resize(n << 1); double_up(n, p.data()); } // O(n * m) static vector convolute_naive(const vector &p, const vector &q){ vector res(max((int)p.size() + (int)q.size() - 1, 0)); for(auto i = 0; i < (int)p.size(); ++ i) for(auto j = 0; j < (int)q.size(); ++ j) res[i + j] += p[i] * q[j]; return res; } // O((n + m) * log(n + m)) static vector convolute(const vector &p, const vector &q){ if(min(p.size(), q.size()) < 55) return convolute_naive(p, q); int m = (int)p.size() + (int)q.size() - 1, n = 1 << __lg(m) + 1; buffer1.assign(n, 0); copy(p.begin(), p.end(), buffer1.begin()); transform(buffer1); buffer2.assign(n, 0); copy(q.begin(), q.end(), buffer2.begin()); transform(buffer2); for(auto i = 0; i < n; ++ i) buffer1[i] *= buffer2[i]; transform(buffer1, true); return vector(buffer1.begin(), buffer1.begin() + m); } // O((n + m) * log(n + m)) static vector arbitrarily_convolute(const vector &p, const vector &q){ using modular0 = modular_fixed_base<1045430273>; using modular1 = modular_fixed_base<1051721729>; using modular2 = modular_fixed_base<1053818881>; using ntt0 = number_theoric_transform_wrapper; using ntt1 = number_theoric_transform_wrapper; using ntt2 = number_theoric_transform_wrapper; vector p0((int)p.size()), q0((int)q.size()); for(auto i = 0; i < (int)p.size(); ++ i) p0[i] = p[i].data; for(auto i = 0; i < (int)q.size(); ++ i) q0[i] = q[i].data; auto xy0 = ntt0::convolute(p0, q0); vector p1((int)p.size()), q1((int)q.size()); for(auto i = 0; i < (int)p.size(); ++ i) p1[i] = p[i].data; for(auto i = 0; i < (int)q.size(); ++ i) q1[i] = q[i].data; auto xy1 = ntt1::convolute(p1, q1); vector p2((int)p.size()), q2((int)q.size()); for(auto i = 0; i < (int)p.size(); ++ i) p2[i] = p[i].data; for(auto i = 0; i < (int)q.size(); ++ i) q2[i] = q[i].data; auto xy2 = ntt2::convolute(p2, q2); static const modular1 r01 = 1 / modular1(modular0::mod()); static const modular2 r02 = 1 / modular2(modular0::mod()); static const modular2 r12 = 1 / modular2(modular1::mod()); static const modular2 r02r12 = r02 * r12; static const T w1 = modular0::mod(); static const T w2 = w1 * modular1::mod(); int n = (int)p.size() + (int)q.size() - 1; vector res(n); for(auto i = 0; i < n; ++ i){ using ull = unsigned long long; ull a = xy0[i].data; ull b = (xy1[i].data + modular1::mod() - a) * r01.data % modular1::mod(); ull c = ((xy2[i].data + modular2::mod() - a) * r02r12.data + (modular2::mod() - b) * r12.data) % modular2::mod(); res[i] = xy0[i].data + w1 * b + w2 * c; } return res; } }; template vector number_theoric_transform_wrapper::root; template vector number_theoric_transform_wrapper::buffer1; template vector number_theoric_transform_wrapper::buffer2; using ntt = number_theoric_transform_wrapper; // T must support *=, *, +=, -=, and - // T{} should return the additive identity // Requires modular and number_theoric_transform template struct power_series_base: vector{ #define data (*this) template power_series_base(Args... args): vector(args...){} power_series_base(initializer_list init): vector(init){} operator bool() const{ return find_if(data.begin(), data.end(), [&](const T &x){ return x != T{0}; }) != data.end(); } // Returns \sum_{i=0}^{n-1} a_i/i! * X^i static power_series_base EGF(vector a){ int n = (int)a.size(); T fact = 1; for(auto x = 2; x < n; ++ x) fact *= x; fact = 1 / fact; for(auto i = n - 1; i >= 0; -- i) a[i] *= fact, fact *= i; return power_series_base(a); } // Returns exp(coef * X).prefix(n) = \sum_{i=0}^{n-1} coef^i/i! * X^i static power_series_base EGF(int n, T coef = 1){ vector a(n, 1); for(auto i = 1; i < n; ++ i) a[i] = a[i - 1] * coef; return EGF(a); } vector EGF_to_seq() const{ int n = (int)data.size(); vector seq(n); T fact = 1; for(auto i = 0; i < n; ++ i){ seq[i] = data[i] * fact; fact *= i + 1; } return seq; } power_series_base &reduce(){ while(!data.empty() && !data.back()) data.pop_back(); return *this; } power_series_base reduced() const{ return power_series_base(*this).reduce(); } friend ostream &operator<<(ostream &out, const power_series_base &p){ if(p.empty()) return out << "{}"; else{ out << "{"; for(auto i = 0; i < (int)p.size(); ++ i){ out << p[i]; i + 1 < (int)p.size() ? out << ", " : out << "}"; } return out; } } power_series_base &inplace_take(int n){ data.erase(data.begin() + min((int)data.size(), n), data.end()); data.resize(n, T{}); return *this; } power_series_base take(int n) const{ return power_series_base(*this).inplace_take(n); } power_series_base &inplace_drop(int n){ data.erase(data.begin(), data.begin() + min((int)data.size(), n)); return *this; } power_series_base drop(int n) const{ return power_series_base(*this).inplace_drop(n); } power_series_base &inplace_reverse(int n){ data.resize(max(n, (int)data.size())); std::reverse(data.begin(), data.begin() + n); return *this; } power_series_base reverse(int n) const{ return power_series_base(*this).inplace_reverse(n); } T evaluate(T x) const{ T res = {}; for(auto i = (int)data.size() - 1; i >= 0; -- i) res = res * x + data[i]; return res; } power_series_base operator*(const power_series_base &p) const{ return FFT::convolute(data, p); } power_series_base &operator*=(const power_series_base &p){ return *this = *this * p; } template power_series_base &operator*=(U x){ for(auto &c: data) c *= x; return *this; } template power_series_base operator*(U x) const{ return power_series_base(*this) *= x; } template friend power_series_base operator*(U x, power_series_base p){ for(auto &c: p) c = x * c; return p; } power_series_base &operator+=(const power_series_base &p){ data.resize(max(data.size(), p.size())); for(auto i = 0; i < (int)p.size(); ++ i) data[i] += p[i]; return *this; } power_series_base operator+(const power_series_base &p) const{ return power_series_base(*this) += p; } template power_series_base &operator+=(const U &x){ if(data.empty()) data.emplace_back(); data[0] += x; return *this; } template power_series_base operator+(const U &x) const{ return power_series_base(*this) += x; } template friend power_series_base operator+(const U &x, const power_series_base &p){ return p + x; } power_series_base &operator-=(const power_series_base &p){ data.resize(max(data.size(), p.size())); for(auto i = 0; i < (int)p.size(); ++ i) data[i] -= p[i]; return *this; } power_series_base operator-(const power_series_base &p) const{ return power_series_base(*this) -= p; } template power_series_base &operator-=(const U &x){ if(data.empty()) data.emplace_back(); data[0] -= x; return *this; } template power_series_base operator-(const U &x) const{ return power_series_base(*this) -= x; } template friend power_series_base operator-(const U &x, const power_series_base &p){ return -p + x; } power_series_base operator-() const{ power_series_base res = *this; for(auto i = 0; i < data.size(); ++ i) res[i] = T{} - res[i]; return res; } power_series_base &operator++(){ if(data.empty()) data.push_back(1); else ++ data[0]; return *this; } power_series_base &operator--(){ if(data.empty()) data.push_back(-1); else -- data[0]; return *this; } power_series_base operator++(int){ power_series_base result(*this); if(data.empty()) data.push_back(1); else ++ data[0]; return result; } power_series_base operator--(int){ power_series_base result(*this); if(data.empty()) data.push_back(-1); else -- data[0]; return result; } power_series_base &clear_range(int l, int r){ assert(0 <= l && l <= r && r <= data.size()); for(auto i = l; i < r; ++ i) data[i] = 0; return *this; } power_series_base &transform(bool invert = false){ FFT::transform(data, invert); return *this; } power_series_base transformed(bool invert = false) const{ auto res = *this; res.transform(invert); return res; } power_series_base &inplace_dot_product(const power_series_base &p){ for(auto i = 0; i < min(data.size(), p.size()); ++ i) data[i] *= p[i]; return *this; } power_series_base dot_product(const power_series_base &p) const{ return power_series_base(*this).inplace_power_series_product(p); } power_series_base &inverse_doubled_up(power_series_base &f, const power_series_base &freq) const{ assert((f.size() & -f.size()) == f.size()); int s = f.size(); power_series_base buffer = take(s << 1); buffer.transform(); buffer.inplace_dot_product(freq); buffer.transform(true); buffer.clear_range(0, s); buffer.transform(); buffer.inplace_dot_product(freq); buffer.transform(true); f.resize(s << 1); return f -= buffer.clear_range(0, s); } power_series_base &inverse_doubled_up(power_series_base &f) const{ assert((f.size() & -f.size()) == f.size()); return inverse_doubled_up(f, f.take(f.size() << 1).transformed()); } // Returns the first n terms of the inverse series // O(n * log(n)) power_series_base inverse(int n) const{ assert(!data.empty() && data[0]); auto inv = 1 / data[0]; power_series_base res{inv}; for(auto s = 1; s < n; s <<= 1) inverse_doubled_up(res); res.resize(n); return res; } // Returns the first n terms of the inverse series // O(n * log(n)) power_series_base &inplace_inverse(int n){ return *this = this->inverse(n); } // O(n * log(n)) power_series_base &inplace_power_series_division(power_series_base p, int n){ int i = 0; while(i < min(data.size(), p.size()) && !data[i] && !p[i]) ++ i; data.erase(data.begin(), data.begin() + i); p.erase(p.begin(), p.begin() + i); (*this *= p.inverse(n)).resize(n); return *this; } // O(n * log(n)) power_series_base power_series_division(const power_series_base &p, int n){ return power_series_base(*this).inplace_power_series_division(p, n); } // Euclidean division // O(n * log(n)) power_series_base &operator/=(const power_series_base &p){ int n = (int)p.size(); while(n && p[n - 1] == T{0}) -- n; assert(n >= 1); reduce(); if(data.size() < n){ data.clear(); return *this; } if(n - count(p.begin(), p.begin() + n, 0) <= 100){ T inv = 1 / p[n - 1]; static vector indices; for(auto i = 0; i < n - 1; ++ i) if(p[i]) indices.push_back(i); power_series_base res((int)data.size() - n + 1); for(auto i = (int)data.size() - 1; i >= n - 1; -- i) if(data[i]){ T x = data[i] * inv; res[i - n + 1] = x; for(auto j: indices) data[i - (n - 1 - j)] -= x * p[j]; } indices.clear(); return *this = res; } power_series_base b; n = data.size() - p.size() + 1; b.assign(n, {}); copy(p.rbegin(), p.rbegin() + min(p.size(), b.size()), b.begin()); std::reverse(data.begin(), data.end()); data = FFT::convolute(data, b.inverse(n)); data.erase(data.begin() + n, data.end()); std::reverse(data.begin(), data.end()); return *this; } power_series_base operator/(const power_series_base &p) const{ return power_series_base(*this) /= p; } template power_series_base &operator/=(U x){ assert(x); T inv_x = T(1) / x; for(auto &c: data) c *= inv_x; return *this; } template power_series_base operator/(U x) const{ return power_series_base(*this) /= x; } pair divrem(const power_series_base &p) const{ auto q = *this / p, r = *this - q * p; while(!r.empty() && r.back() == 0) r.pop_back(); return {q, r}; } power_series_base &operator%=(const power_series_base &p){ int n = (int)p.size(); while(n && p[n - 1] == T{0}) -- n; assert(n >= 1); reduce(); if(data.size() < n) return *this; if(n - count(p.begin(), p.begin() + n, 0) <= 100){ T inv = 1 / p[n - 1]; static vector indices; for(auto i = 0; i < n - 1; ++ i) if(p[i]) indices.push_back(i); for(auto i = (int)data.size() - 1; i >= n - 1; -- i) if(data[i]){ T x = data[i] * inv; data[i] = 0; for(auto j: indices) data[i - (n - 1 - j)] -= x * p[j]; } indices.clear(); return reduce(); } return *this = this->divrem(p).second; } power_series_base operator%(const power_series_base &p) const{ return power_series_base(*this) %= p; } power_series_base &inplace_derivative(){ if(!data.empty()){ for(auto i = 0; i < data.size(); ++ i) data[i] *= i; data.erase(data.begin()); } return *this; } // p' power_series_base derivative() const{ return power_series_base(*this).inplace_derivative(); } power_series_base &inplace_derivative_shift(){ for(auto i = 0; i < data.size(); ++ i) data[i] *= i; return *this; } // xP' power_series_base derivative_shift() const{ return power_series_base(*this).inplace_derivative_shift(); } power_series_base &inplace_antiderivative(){ T::precalc_inverse(data.size()); data.push_back(0); for(auto i = (int)data.size() - 1; i >= 1; -- i) data[i] = data[i - 1] / i; data[0] = 0; return *this; } // Integral(P) power_series_base antiderivative() const{ return power_series_base(*this).inplace_antiderivative(); } power_series_base &inplace_shifted_antiderivative(){ T::precalc_inverse(data.size()); if(!data.empty()) data[0] = 0; for(auto i = 1; i < data.size(); ++ i) data[i] /= i; return *this; } // Integral(P/x) power_series_base shifted_antiderivative() const{ return power_series_base(*this).inplace_shifted_antiderivative(); } // O(n * log(n)) power_series_base &inplace_log(int n){ assert(!data.empty() && data[0] == 1); if(!n){ data.clear(); return *this; } (*this = derivative() * inverse(n)).resize(n - 1); inplace_antiderivative(); return *this; } // O(n * log(n)) power_series_base log(int n) const{ return power_series_base(*this).inplace_log(n); } // O(n * log(n)) power_series_base exp(int n) const{ assert(data.empty() || data[0] == 0); power_series_base f{1}, g{1}; for(auto s = 1; s < n; s <<= 1){ power_series_base f2 = f.take(s << 1).transform(); power_series_base g2 = g.take(s << 1).transform(); power_series_base dt = take(s).inplace_derivative_shift(); power_series_base w = dt; w.transform(); for(auto i = 0; i < s; ++ i) w[i] *= f2[i << 1]; w.transform(true); w -= f.derivative_shift(); w.resize(s << 1); w.transform(); w.inplace_dot_product(g2); w.transform(true); w.resize(s); w.insert(w.begin(), s, 0); w -= dt; power_series_base z = take(s << 1); z += w.inplace_shifted_antiderivative(); z.transform(); z.inplace_dot_product(f2); z.transform(true); f.resize(s << 1); f += z.clear_range(0, s); if(s << 1 < n) f.inverse_doubled_up(g, g2); } f.resize(n); return f; } // O(n * log(n)) power_series_base &inplace_exp(int n){ return *this = this->exp(n); } // O(n * log(n)) template power_series_base &inplace_power(U e, int n){ data.resize(n); if(e == 0 || n == 0){ if(n) data[0] = 1; return *this; } if(e < 0) return inplace_inverse(n).inplace_power(-e, n); if(all_of(data.begin(), data.end(), [&](auto x){ return x == 0; })) return *this; int pivot = find_if(data.begin(), data.end(), [&](auto x){ return x; }) - data.begin(); if(pivot && e >= (n + pivot - 1) / pivot){ fill(data.begin(), data.end(), 0); return *this; } data.erase(data.begin(), data.begin() + pivot); n -= pivot * e; T pivot_c = data[0].power(e); ((*this /= data[0]).inplace_log(n) *= e).inplace_exp(n); data.insert(data.begin(), pivot * e, 0); return *this *= pivot_c; } // O(n * log(n)) template power_series_base power(U e, int n) const{ return power_series_base(*this).inplace_power(e, n); } static power_series_base multiply_all(const vector &a){ if(a.empty()) return {1}; auto solve = [&](auto self, int l, int r)->power_series_base{ if(r - l == 1) return a[l]; int m = l + (r - l >> 1); return self(self, l, m) * self(self, m, r); }; return solve(solve, 0, (int)a.size()); } #undef data }; using power_series = power_series_base; int main(){ cin.tie(0)->sync_with_stdio(0); cin.exceptions(ios::badbit | ios::failbit); int n, m; cin >> n >> m; combinatorics C(max(n, m) * 2); power_series p(2 * m + 1), q{0, 2, 1}; for(auto i = 1; i <= 2 * m; ++ i){ p[i] = C.C(2 * m, i); } cout << p.power_series_division(q, n)[n - 1] << "\n"; return 0; } /* 1 + (1+2x+x^2) + ... + (1+2x+x^2)^{m-1} = ((1+x)^2m-1)/(2x+x^2) */ //////////////////////////////////////////////////////////////////////////////////////// // // // Coded by Aeren // // // ////////////////////////////////////////////////////////////////////////////////////////