#include //#include //#include //#include #define rep(i, a) for (int i = (int)0; i < (int)a; ++i) #define rrep(i, a) for (int i = (int)a - 1; i >= 0; --i) #define REP(i, a, b) for (int i = (int)a; i < (int)b; ++i) #define RREP(i, a, b) for (int i = (int)a - 1; i >= b; --i) #define repl(i, a) for (ll i = (ll)0; i < (ll)a; ++i) #define pb push_back #define eb emplace_back #define all(x) x.begin(), x.end() #define rall(x) x.rbegin(), x.rend() #define popcount __builtin_popcount #define fi first #define se second using ll = long long; constexpr ll mod = 1e9 + 7; constexpr ll mod_998244353 = 998244353; constexpr ll INF = 1LL << 60; // #pragma GCC target("avx2") // #pragma GCC optimize("O3") // #pragma GCC optimize("unroll-loops") //using lll=boost::multiprecision::cpp_int; //using Double=boost::multiprecision::number>;//仮数部が1024桁 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; } template T mypow(T x, T n, const T &p = -1) { //x^nをmodで割った余り if (p != -1) { x %= p; } T ret = 1; while (n > 0) { if (n & 1) { if (p != -1) ret = (ret * x) % p; else ret *= x; } if (p != -1) x = (x * x) % p; else x *= x; n >>= 1; } return ret; } using namespace std; //using namespace atcoder; template struct Modint{ int x; Modint():x(0){} Modint(int64_t y):x((y%mod+mod)%mod){} Modint &operator+=(const Modint &p){ if((x+=p.x)>=mod) x -= mod; return *this; } Modint &operator-=(const Modint &p){ if((x+=mod-p.x)>=mod) x -= mod; return *this; } Modint &operator*=(const Modint &p){ x = (1LL * x * p.x) % mod; return *this; } Modint &operator/=(const Modint &p){ *this *= p.inverse(); return *this; } Modint operator-() const { return Modint(-x); } Modint operator+(const Modint &p) const{ return Modint(*this) += p; } Modint operator-(const Modint &p) const{ return Modint(*this) -= p; } Modint operator*(const Modint &p) const{ return Modint(*this) *= p; } Modint operator/(const Modint &p) const{ return Modint(*this) /= p; } bool operator==(const Modint &p) const { return x == p.x; } bool operator!=(const Modint &p) const{return x != p.x;} Modint inverse() const{//非再帰拡張ユークリッド int a = x, b = mod, u = 1, v = 0; while(b>0){ int t = a / b; swap(a -= t * b, b); swap(u -= t * v, v); } return Modint(u); } Modint pow(int64_t n) const{//繰り返し二乗法 Modint ret(1), mul(x); while(n>0){ if(n&1) ret *= mul; mul *= mul; n >>= 1; } return ret; } friend ostream &operator<<(ostream &os,const Modint &p){ return os << p.x; } }; using modint = Modint; using modint2= Modint; template struct Combination{ //Modint用 //構築O(N),クエリO(1) vectorfact,rfact; Combination(int n):fact(n+1),rfact(n+1){ fact[0]=1;fact[1]=1; rfact[n]=1; for(int i=2;i<=n;++i){ fact[i]=fact[i-1]*i; } rfact[n]/=fact[n]; for(int i=n-1;i>=0;--i){ rfact[i]=rfact[i+1]*(i+1); } } T C(int n,int r) const{ if(n==-1&&r==0)return 1;//0H0のとき if(r<0 || n>n>>m>>a>>b; modint2 ans=0; Combinationc(m+b+n+5); for(ll i=1;i<=m;++i){ ll x=min(m-i,b)-(n-1)*a; if(x<0)continue; modint2 res=1; res*=c.C(x+n-1,x); res*=c.fact[n]; ans+=res; } cout<