#include using namespace std; #pragma GCC optimize("Ofast") #define rep(i,n) for(ll i=0;i=0;i--) #define perl(i,r,l) for(ll i=r-1;i>=l;i--) #define fi first #define se second #define pb push_back #define ins insert #define pqueue(x) priority_queue,greater> #define all(x) (x).begin(),(x).end() #define CST(x) cout<> #define rev(x) reverse(x); using ll=long long; using vl=vector; using vvl=vector>; using pl=pair; using vpl=vector; using vvpl=vector; const ll MOD=1000000007; const ll MOD9=998244353; const int inf=1e9+10; const ll INF=4e18; const ll dy[9]={1,0,-1,0,1,1,-1,-1,0}; const ll dx[9]={0,1,0,-1,1,-1,1,-1,0}; template inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; } template inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; } const int mod = MOD; const int max_n = 200005; struct mint { ll x; // typedef long long ll; mint(ll x=0):x((x%mod+mod)%mod){} mint operator-() const { return mint(-x);} mint& operator+=(const mint a) { if ((x += a.x) >= mod) x -= mod; return *this; } mint& operator-=(const mint a) { if ((x += mod-a.x) >= mod) x -= mod; return *this; } mint& operator*=(const mint a) { (x *= a.x) %= mod; return *this;} mint operator+(const mint a) const { return mint(*this) += a;} mint operator-(const mint a) const { return mint(*this) -= a;} mint operator*(const mint a) const { return mint(*this) *= a;} mint pow(ll t) const { if (!t) return 1; mint a = pow(t>>1); a *= a; if (t&1) a *= *this; return a; } bool operator==(const mint &p) const { return x == p.x; } bool operator!=(const mint &p) const { return x != p.x; } // for prime mod mint inv() const { return pow(mod-2);} mint& operator/=(const mint a) { return *this *= a.inv();} mint operator/(const mint a) const { return mint(*this) /= a;} }; istream& operator>>(istream& is, mint& a) { return is >> a.x;} ostream& operator<<(ostream& os, const mint& a) { return os << a.x;} using vm=vector; using vvm=vector; struct combination { vector fact, ifact; combination(int n):fact(n+1),ifact(n+1) { assert(n < mod); fact[0] = 1; for (int i = 1; i <= n; ++i) fact[i] = fact[i-1]*i; ifact[n] = fact[n].inv(); for (int i = n; i >= 1; --i) ifact[i-1] = ifact[i]*i; } mint operator()(int n, int k) { if (k < 0 || k > n) return 0; return fact[n]*ifact[k]*ifact[n-k]; } }comb(max_n); namespace NTT { // int32型のmodが取れるFFT。auto c=NTT::mul(a,b,mod)で受け取り。TIME指定。 // ChineseRemと組み合わせてlong longにもできる std::vector tmp; size_t sz = 1; inline int powMod(int n, int p, int m) { int res = 1; while (p) { if (p & 1) res = (ll)res * n % m; n = (ll)n * n % m; p >>= 1; } return (int)res; } inline int invMod(int n, int m) { return powMod(n, m - 2, m); } template struct NTTPart { static std::vector ntt(std::vector a, bool inv = false) { size_t mask = sz - 1; size_t p = 0; for (size_t i = sz >> 1; i >= 1; i >>= 1) { auto& cur = (p & 1) ? tmp : a; auto& nex = (p & 1) ? a : tmp; int e = powMod(PrimitiveRoot, (Mod - 1) / sz * i, Mod); if (inv) e = invMod(e, Mod); int w = 1; for (size_t j = 0; j < sz; j += i) { for (size_t k = 0; k < i; ++k) { nex[j + k] = (cur[((j << 1) & mask) + k] + (ll)w * cur[(((j << 1) + i) & mask) + k]) % Mod; } w = (ll)w * e % Mod; } ++p; } if (p & 1) std::swap(a, tmp); if (inv) { int invSz = invMod(sz, Mod); for (size_t i = 0; i < sz; ++i) a[i] = (ll)a[i] * invSz % Mod; } return a; } static std::vector mul(std::vector a, std::vector b) { a = ntt(a); b = ntt(b); for (size_t i = 0; i < sz; ++i) a[i] = (ll)a[i] * b[i] % Mod; a = ntt(a, true); return a; } }; constexpr int M[] = {1224736769, 469762049, 167772161}; constexpr int PR[] = {3, 3, 3}; constexpr int NTT_CONVOLUTION_TIME = 3; /* X := max(a)*max(b)*max(|a|, |b|) のとき, NTT_CONVOLUTION_TIME <- 1: X < 1224736769 = 1.2*10^ 9 ~ 2^30 NTT_CONVOLUTION_TIME <- 2: X < 575334854091079681 = 5.8*10^17 ~ 2^59 NTT_CONVOLUTION_TIME <- 3: X < 2^86 (32bit * 32bit * 10^7くらいまで) */ inline void garner(std::vector *c, int mod) { if (NTT_CONVOLUTION_TIME == 1) { for(auto& x : c[0]) x %= mod; } else if (NTT_CONVOLUTION_TIME == 2) { const int r01 = invMod(M[0], M[1]); for (size_t i = 0; i < sz; ++i) { c[1][i] = (c[1][i] - c[0][i]) * (ll)r01 % M[1]; if (c[1][i] < 0) c[1][i] += M[1]; c[0][i] = (c[0][i] + (ll)c[1][i] * M[0]) % mod; } } else if (NTT_CONVOLUTION_TIME == 3) { const int R01 = invMod(M[0], M[1]); const int R02 = invMod(M[0], M[2]); const int R12 = invMod(M[1], M[2]); const int M01 = (ll)M[0] * M[1] % mod; for (size_t i = 0; i < sz; ++i) { c[1][i] = (c[1][i] - c[0][i]) * (ll)R01 % M[1]; if (c[1][i] < 0) c[1][i] += M[1]; c[2][i] = ((c[2][i] - c[0][i]) * (ll)R02 % M[2] - c[1][i]) * R12 % M[2]; if (c[2][i] < 0) c[2][i] += M[2]; c[0][i] = (c[0][i] + (ll)c[1][i] * M[0] + (ll)c[2][i] * M01) % mod; } } } std::vector mul(std::vector a, std::vector b, int mod) { for (auto& x : a) x %= mod; for (auto& x : b) x %= mod; size_t m = a.size() + b.size() - 1; sz = 1; while (m > sz) sz <<= 1; tmp.resize(sz); a.resize(sz, 0); b.resize(sz, 0); std::vector c[NTT_CONVOLUTION_TIME]; if (NTT_CONVOLUTION_TIME >= 1) c[0] = NTTPart::mul(a, b); if (NTT_CONVOLUTION_TIME >= 2) c[1] = NTTPart::mul(a, b); if (NTT_CONVOLUTION_TIME >= 3) c[2] = NTTPart::mul(a, b); for (auto& v : c) v.resize(m); garner(c, mod); return c[0]; } }; // !!! CHECK NTT_CONVOLUTION_TIME !!! vector BerlekampMassey(const vector &s) { const int N = (int)s.size(); vector b, c; b.reserve(N + 1); c.reserve(N + 1); b.push_back(mint(1)); c.push_back(mint(1)); mint y = mint(1); for (int ed = 1; ed <= N; ed++) { int l = int(c.size()), m = int(b.size()); mint x = 0; for (int i = 0; i < l; i++) x += c[i] * s[ed - l + i]; b.emplace_back(mint(0)); m++; if (x == mint(0)) continue; mint freq = x / y; if (l < m) { auto tmp = c; c.insert(begin(c), m - l, mint(0)); for (int i = 0; i < m; i++) c[m - 1 - i] -= freq * b[m - 1 - i]; b = tmp; y = x; } else { for (int i = 0; i < m; i++) c[l - 1 - i] -= freq * b[m - 1 - i]; } } reverse(begin(c), end(c)); return c; } template vector kitamasa(vector Q,vector a) { assert(!Q.empty() && Q[0] != 0); assert((int)a.size() >= int(Q.size()) - 1); vector P(Q.size()*2-2); for(ll i=0;i struct bostan_mori { vector p, q; bostan_mori(vector &_p, vector &_q) : p(_p), q(_q) {} void rever(vector &f) const { int d = f.size(); rep(i, d) if (i&1) f[i] = -f[i]; } void even(vector &f) const { int d = (f.size() + 1) >> 1; rep(i, d) f[i] = f[i<<1]; f.resize(d); } void odd(vector &f) const { int d = f.size() >> 1; rep(i, d) f[i] = f[i<<1|1]; f.resize(d); } vector convolution(vector a,vector b) const{ ll n=a.size(),m=b.size(); vector na(n),nb(m); rep(i,n)na[i]=a[i].x; rep(i,m)nb[i]=b[i].x; auto f=NTT::mul(na,nb,MOD); vector c(n+m-1); rep(i,n+m-1)c[i]=f[i]; return c; } T operator[] (ll n) const { vector _p(p), _q(q), _q_rev(q); rever(_q_rev); for (; n; n >>= 1) { _p = convolution(move(_p), _q_rev); if (n&1) odd(_p); else even(_p); _q = convolution(move(_q), move(_q_rev)); even(_q); _q_rev = _q; rever(_q_rev); } return _p[0] / _q[0]; } }; ll m; //https://nyaannyaan.github.io/library/fps/kitamasa.hpp //https://atcoder.jp/contests/tdpc/submissions/34362182 //線形漸化式のprefixからn項目を復元できる。 bostan_mori interpolation(){ vm p={0,1}; vm q(m+3); q[0]+=1;q[1]-=1;q[2]-=1; q[m]-=1;q[m+1]+=1;q[m+2]+=1; return bostan_mori(p,q); } int main(){ ll n;cin >> n>> m; auto f=interpolation(); cout << f[n*m] << endl; }