// #pragma GCC optimize("O3,unroll-loops") #include // #include using namespace std; #if __cplusplus >= 202002L using namespace numbers; #endif template struct modular_fixed_base{ #define IS_INTEGRAL(T) (is_integral_v || is_same_v || is_same_v) #define IS_UNSIGNED(T) (is_unsigned_v || is_same_v) static_assert(IS_UNSIGNED(data_t)); static_assert(_mod >= 1); static constexpr bool VARIATE_MOD_FLAG = false; static constexpr data_t 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; data_t divs[20] = {}; divs[0] = 2; int cnt = 1; data_t 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(){ } modular_fixed_base(const double &x){ data = _normalize(llround(x)); } modular_fixed_base(const long double &x){ data = _normalize(llround(x)); } template::type* = nullptr> modular_fixed_base(const T &x){ data = _normalize(x); } template::type* = nullptr> static data_t _normalize(const T &x){ int sign = x >= 0 ? 1 : -1; data_t v = _mod <= sign * x ? sign * x % _mod : sign * x; if(sign == -1 && v) v = _mod - v; return v; } template::type* = nullptr> 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::type* = nullptr> modular_fixed_base &operator+=(const T &otr){ return *this += modular_fixed_base(otr); } template::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){ if constexpr(is_same_v) data = (unsigned long long)data * rhs.data % _mod; else if constexpr(is_same_v){ long long res = data * rhs.data - _mod * (unsigned long long)(1.L / _mod * data * rhs.data); data = res + _mod * (res < 0) - _mod * (res >= (long long)_mod); } else data = _normalize(data * rhs.data); return *this; } template::type* = nullptr> modular_fixed_base &inplace_power(T e){ if(e == 0) return *this = 1; if(data == 0) return *this = {}; if(data == 1 || e == 1) return *this; if(data == mod() - 1) return e % 2 ? *this : *this = -*this; if(e < 0) *this = 1 / *this, e = -e; if(e == 1) return *this; modular_fixed_base res = 1; for(; e; *this *= *this, e >>= 1) if(e & 1) res *= *this; return *this = res; } template::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){ make_signed_t a = otr.data, m = _mod, u = 0, v = 1; if(a < _INV.size()) return *this *= _INV[a]; while(a){ make_signed_t t = m / a; m -= t * a; swap(a, m); u -= t * v; swap(u, v); } assert(m == 1); return *this *= u; } #define ARITHMETIC_OP(op, apply_op)\ modular_fixed_base operator op(const modular_fixed_base &x) const{ return modular_fixed_base(*this) apply_op x; }\ template::type* = nullptr>\ modular_fixed_base operator op(const T &x) const{ return modular_fixed_base(*this) apply_op modular_fixed_base(x); }\ template::type* = nullptr>\ friend modular_fixed_base operator op(const T &x, const modular_fixed_base &y){ return modular_fixed_base(x) apply_op y; } ARITHMETIC_OP(+, +=) ARITHMETIC_OP(-, -=) ARITHMETIC_OP(*, *=) ARITHMETIC_OP(/, /=) #undef ARITHMETIC_OP #define COMPARE_OP(op)\ bool operator op(const modular_fixed_base &x) const{ return data op x.data; }\ template::type* = nullptr>\ bool operator op(const T &x) const{ return data op modular_fixed_base(x).data; }\ template::type* = nullptr>\ friend bool operator op(const T &x, const modular_fixed_base &y){ return modular_fixed_base(x).data op y.data; } COMPARE_OP(==) COMPARE_OP(!=) COMPARE_OP(<) COMPARE_OP(<=) COMPARE_OP(>) COMPARE_OP(>=) #undef COMPARE_OP friend istream &operator>>(istream &in, modular_fixed_base &number){ long long x; in >> x; number.data = modular_fixed_base::_normalize(x); return in; } //#define _SHOW_FRACTION friend ostream &operator<<(ostream &out, const modular_fixed_base &number){ out << number.data; #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; } data_t data = 0; #undef _SHOW_FRACTION #undef IS_INTEGRAL #undef IS_UNSIGNED }; template vector> modular_fixed_base::_INV; template modular_fixed_base modular_fixed_base::_primitive_root; const unsigned int mod = (119 << 23) + 1; // 998244353 // const unsigned int mod = 1e9 + 7; // 1000000007 // const unsigned int mod = 1e9 + 9; // 1000000009 // const unsigned long long mod = (unsigned long long)1e18 + 9; using modular = modular_fixed_base, mod>; template struct power_series_naive_base: vector{ #define data (*this) template power_series_naive_base(Args... args): vector(args...){} power_series_naive_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_naive_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_naive_base(a); } // Returns exp(coef * X).take(n) = \sum_{i=0}^{n-1} coef^i/i! * X^i static power_series_naive_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_naive_base &inplace_reduce(){ while(!data.empty() && !data.back()) data.pop_back(); return *this; } power_series_naive_base reduce() const{ return power_series_naive_base(*this).inplace_reduce(); } friend ostream &operator<<(ostream &out, const power_series_naive_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_naive_base &inplace_take(int n){ data.erase(data.begin() + min((int)data.size(), n), data.end()); data.resize(n, T{0}); return *this; } power_series_naive_base take(int n) const{ auto res = vector(data.begin(), data.begin() + min((int)data.size(), n)); res.resize(n, T{0}); return res; } power_series_naive_base &inplace_drop(int n){ data.erase(data.begin(), data.begin() + min((int)data.size(), n)); return *this; } power_series_naive_base drop(int n) const{ return vector(data.begin() + min((int)data.size(), n), data.end()); } power_series_naive_base &inplace_slice(int l, int r){ assert(0 <= l && l <= r); data.erase(data.begin(), data.begin() + min((int)data.size(), l)); data.resize(r - l, T{0}); return *this; } power_series_naive_base slice(int l, int r) const{ auto res = vector(data.begin() + min((int)data.size(), l), data.begin() + min((int)data.size(), r)); res.resize(r - l, T{0}); return res; } power_series_naive_base &inplace_reverse(int n){ data.resize(max(n, (int)data.size()), T{0}); std::reverse(data.begin(), data.begin() + n); return *this; } power_series_naive_base reverse(int n) const{ return power_series_naive_base(*this).inplace_reverse(n); } power_series_naive_base &inplace_shift(int n, T x = T{0}){ data.insert(data.begin(), n, x); return *this; } power_series_naive_base shift(int n, T x = T{0}) const{ return power_series_naive_base(*this).inplace_shift(n, x); } T evaluate(T x) const{ T res = {}; for(auto i = (int)data.size() - 1; i >= 0; -- i) res = res * x + data[i]; return res; } // Takes mod x^n-1 power_series_naive_base &inplace_circularize(int n){ assert(n >= 1); for(auto i = n; i < (int)data.size(); ++ i) data[i % n] += data[i]; data.resize(n, T{0}); return *this; } // Takes mod x^n-1 power_series_naive_base circularize(int n) const{ return power_series_naive_base(*this).inplace_circularize(n); } power_series_naive_base operator*(const power_series_naive_base &p) const{ return multiplication_functor::multiply(data, p); } power_series_naive_base &operator*=(const power_series_naive_base &p){ return *this = *this * p; } template power_series_naive_base &operator*=(U x){ for(auto &c: data) c *= x; return *this; } template power_series_naive_base operator*(U x) const{ return power_series_naive_base(*this) *= x; } template friend power_series_naive_base operator*(U x, power_series_naive_base p){ for(auto &c: p) c = x * c; return p; } // Compute p^e mod x^n - 1. template power_series_naive_base &inplace_power_circular(U e, int n){ assert(n >= 1); power_series_naive_base p = *this; data.assign(n, 0); data[0] = 1; for(; e; e >>= 1){ if(e & 1) (*this *= p).inplace_circularize(n); (p *= p).inplace_circularize(n); } return *this; } template power_series_naive_base power_circular(U e, int len) const{ return power_series_naive_base(*this).inplace_power_circular(e, len); } power_series_naive_base &operator+=(const power_series_naive_base &p){ resize(max(data.size(), p.size()), T{0}); for(auto i = 0; i < (int)p.size(); ++ i) data[i] += p[i]; return *this; } power_series_naive_base operator+(const power_series_naive_base &p) const{ return power_series_naive_base(*this) += p; } template power_series_naive_base &operator+=(const U &x){ if(data.empty()) data.emplace_back(); data[0] += x; return *this; } template power_series_naive_base operator+(const U &x) const{ return power_series_naive_base(*this) += x; } template friend power_series_naive_base operator+(const U &x, const power_series_naive_base &p){ return p + x; } power_series_naive_base &operator-=(const power_series_naive_base &p){ data.resize(max(data.size(), p.size()), T{0}); for(auto i = 0; i < (int)p.size(); ++ i) data[i] -= p[i]; return *this; } power_series_naive_base operator-(const power_series_naive_base &p) const{ return power_series_naive_base(*this) -= p; } template power_series_naive_base &operator-=(const U &x){ if(data.empty()) data.emplace_back(); data[0] -= x; return *this; } template power_series_naive_base operator-(const U &x) const{ return power_series_naive_base(*this) -= x; } template friend power_series_naive_base operator-(const U &x, const power_series_naive_base &p){ return -p + x; } power_series_naive_base operator-() const{ power_series_naive_base res = *this; for(auto i = 0; i < data.size(); ++ i) res[i] = T{} - res[i]; return res; } power_series_naive_base &operator++(){ if(data.empty()) data.push_back(1); else ++ data[0]; return *this; } power_series_naive_base &operator--(){ if(data.empty()) data.push_back(-1); else -- data[0]; return *this; } power_series_naive_base operator++(int){ power_series_naive_base result(*this); if(data.empty()) data.push_back(1); else ++ data[0]; return result; } power_series_naive_base operator--(int){ power_series_naive_base result(*this); if(data.empty()) data.push_back(-1); else -- data[0]; return result; } power_series_naive_base &inplace_clear_range(int l, int r){ assert(0 <= l && l <= r); for(auto i = l; i < min(r, (int)data.size()); ++ i) data[i] = T{0}; return *this; } power_series_naive_base clear_range(int l, int r) const{ return power_series_naive_base(*this).inplace_clear_range(l, r); } power_series_naive_base &inplace_dot_product(const power_series_naive_base &p){ for(auto i = 0; i < min(data.size(), p.size()); ++ i) data[i] *= p[i]; return *this; } power_series_naive_base dot_product(const power_series_naive_base &p) const{ return power_series_naive_base(*this).inplace_power_series_product(p); } power_series_naive_base inverse(int n) const{ assert(!data.empty() && data[0]); auto inv = 1 / data[0]; power_series_naive_base res{inv}; for(auto s = 1; s < n; s <<= 1) (res *= (2 - res * take(s << 1))).inplace_take(s << 1); return res.inplace_take(n); } power_series_naive_base &inplace_inverse(int n){ return *this = this->inverse(n); } power_series_naive_base &inplace_power_series_division(power_series_naive_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, T{0}); return *this; } power_series_naive_base power_series_division(const power_series_naive_base &p, int n){ return power_series_naive_base(*this).inplace_power_series_division(p, n); } // Euclidean division // O(min(n * log(n), # of non-zero indices)) power_series_naive_base &operator/=(const power_series_naive_base &p){ int n = (int)p.size(); while(n && p[n - 1] == T{0}) -- n; assert(n >= 1); inplace_reduce(); if(data.size() < n){ data.clear(); return *this; } if(n - count(p.begin(), p.begin() + n, T{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_naive_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_naive_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 *= b.inverse(n); data.erase(data.begin() + n, data.end()); std::reverse(data.begin(), data.end()); return *this; } power_series_naive_base operator/(const power_series_naive_base &p) const{ return power_series_naive_base(*this) /= p; } template power_series_naive_base &operator/=(U x){ assert(x); T inv_x = T(1) / x; for(auto &c: data) c *= inv_x; return *this; } template power_series_naive_base operator/(U x) const{ return power_series_naive_base(*this) /= x; } pair divrem(const power_series_naive_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_naive_base &operator%=(const power_series_naive_base &p){ int n = (int)p.size(); while(n && p[n - 1] == T{0}) -- n; assert(n >= 1); inplace_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 inplace_reduce(); } return *this = this->divrem(p).second; } power_series_naive_base operator%(const power_series_naive_base &p) const{ return power_series_naive_base(*this) %= p; } power_series_naive_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_naive_base derivative() const{ return power_series_naive_base(*this).inplace_derivative(); } power_series_naive_base &inplace_derivative_shift(){ for(auto i = 0; i < data.size(); ++ i) data[i] *= i; return *this; } // xP' power_series_naive_base derivative_shift() const{ return power_series_naive_base(*this).inplace_derivative_shift(); } power_series_naive_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_naive_base antiderivative() const{ return power_series_naive_base(*this).inplace_antiderivative(); } power_series_naive_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_naive_base shifted_antiderivative() const{ return power_series_naive_base(*this).inplace_shifted_antiderivative(); } power_series_naive_base &inplace_log(int n){ assert(!data.empty() && data[0] == 1); if(!n){ data.clear(); return *this; } (*this = derivative() * inverse(n)).resize(n - 1, T{0}); inplace_antiderivative(); return *this; } power_series_naive_base log(int n) const{ return power_series_naive_base(*this).inplace_log(n); } power_series_naive_base exp(int n) const{ assert(data.empty() || data[0] == T{0}); power_series_naive_base f{1}, g; for(auto s = 1; s < n; s <<= 1){ g = f.log(s << 1).drop(s) - drop(s).take(s); (f -= (f * g).take(s).shift(s)).inplace_take(s << 1); } return f.take(n); } power_series_naive_base &inplace_exp(int n){ return *this = this->exp(n); } template power_series_naive_base &inplace_power(U e, int n){ data.resize(n, T{0}); 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 == T{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(), T{0}); return *this; } data.erase(data.begin(), data.begin() + pivot); n -= pivot * e; T pivot_c = T{1}, base = data[0]; for(auto x = e; x; x >>= 1, base *= base) if(x & 1) pivot_c *= base; ((*this /= data[0]).inplace_log(n) *= e).inplace_exp(n); data.insert(data.begin(), pivot * e, T{0}); return *this *= pivot_c; } template power_series_naive_base power(U e, int n) const{ return power_series_naive_base(*this).inplace_power(e, n); } // Suppose there are data[i] distinct objects with weight i. // Returns a power series where i-th coefficient represents # of ways to select a set of objects with sum of weight i. // O(n * log(n)) power_series_naive_base &inplace_set(int n){ assert(!data.empty() && data[0] == T{0}); data.resize(n); for(auto i = n - 1; i >= 1; -- i) for(auto j = 2 * i; j < n; j += i) data[j] += data[i]; for(auto i = 1; i < n; ++ i) (data[i] /= i) *= (i & 1 ? 1 : -1); return inplace_exp(n); } power_series_naive_base set(int n) const{ return power_series_naive_base(*this).inplace_set(n); } // Suppose there are data[i] distinct objects with weight i. // Returns a power series where i-th coefficient represents # of ways to select a multiset of objects with sum of weight i. // O(n * log(n)) power_series_naive_base &inplace_multiset(int n){ assert(!data.empty() && data[0] == T{0}); data.resize(n); static vector inv; inv.resize(n); for(auto i = 1; i < n; ++ i) inv[i] = T{1} / i; for(auto i = n - 1; i >= 1; -- i) for(auto j = 2 * i; j < n; j += i) data[j] += data[i] * inv[j / i]; inv.clear(), inv.shrink_to_fit(); return inplace_exp(n); } power_series_naive_base multiset(int n) const{ return power_series_naive_base(*this).inplace_multiset(n); } static power_series_naive_base multiply_all(const vector &a){ if(a.empty()) return {1}; auto solve = [&](auto self, int l, int r)->power_series_naive_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()); } friend power_series_naive_base gcd(power_series_naive_base p, power_series_naive_base q){ while(q) p = exchange(q, p % q); return p; } friend power_series_naive_base lcm(power_series_naive_base p, power_series_naive_base q){ return p / gcd(p, q) * q; } #undef data }; template struct _quadratic{ static vector multiply(const vector &a, const vector &b){ if(a.empty() || b.empty()) return {}; vector q((int)a.size() + (int)b.size() - 1); for(auto i = 0; i < (int)a.size(); ++ i) for(auto j = 0; j < (int)b.size(); ++ j) q[i + j] += a[i] * b[j]; return q; } }; template struct _with_fft{ static vector multiply_naively(const vector &a, const vector &b){ vector q((int)a.size() + (int)b.size() - 1); for(auto i = 0; i < (int)a.size(); ++ i) for(auto j = 0; j < (int)b.size(); ++ j) q[i + j] += a[i] * b[j]; return q; } static vector multiply(const vector &a, const vector &b){ if(a.empty() || b.empty()) return {}; if(min(a.size(), b.size()) <= 60) return multiply_naively(a, b); return FFT::arbitrarily_convolute(a, b); } }; template using power_series = power_series_naive_base>; // using power_series = power_series_naive_base>; int main(){ cin.tie(0)->sync_with_stdio(0); cin.exceptions(ios::badbit | ios::failbit); int n, k; cin >> n >> k; power_series p(6, modular(1) / 6); p.inplace_power_circular(n, 6); cout << p[k] << "\n"; return 0; } /* */