#include <bits/stdc++.h>
#define FOR(v, a, b) for(int v = (a); v < (b); ++v)
#define FORE(v, a, b) for(int v = (a); v <= (b); ++v)
#define REP(v, n) FOR(v, 0, n)
#define REPE(v, n) FORE(v, 0, n)
#define REV(v, a, b) for(int v = (a); v >= (b); --v)
#define ALL(x) (x).begin(), (x).end()
#define ITR(it, c) for(auto it = (c).begin(); it != (c).end(); ++it)
#define RITR(it, c) for(auto it = (c).rbegin(); it != (c).rend(); ++it)
#define EXIST(c,x) ((c).find(x) != (c).end())
#define LLI long long int
#define fst first
#define snd second

#ifdef DEBUG
#include <misc/C++/Debug.cpp>
#else
#define dump(x)
#endif

#define gcd __gcd

using namespace std;
template <class T> constexpr T lcm(T m, T n){return m/gcd(m,n)*n;}

template <typename I> void join(ostream &ost, I s, I t, string d=" "){for(auto i=s; i!=t; ++i){if(i!=s)ost<<d; ost<<*i;}ost<<endl;}
template <typename T> istream& operator>>(istream &is, vector<T> &v){for(auto &a : v) is >> a; return is;}
template <typename T, typename U> istream& operator>>(istream &is, pair<T,U> &p){is >> p.first >> p.second; return is;}

template <typename T, typename U> T& chmin(T &a, const U &b){return a = (a<=b?a:b);}
template <typename T, typename U> T& chmax(T &a, const U &b){return a = (a>=b?a:b);}
template <typename T, size_t N, typename U> void fill_array(T (&a)[N], const U &v){fill((U*)a, (U*)(a+N), v);}

const LLI mod = 1e9+7;

LLI power(LLI n, LLI p, LLI m){
  LLI ret = 1;
  while(p>0){
    if(p&1) (ret *= n) %= m;
    (n *= n) %= m;
    p /= 2;
  }
  return ret;
}

LLI mod_inv(LLI n, LLI p){return power(n,p-2,p);}

int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);

  LLI N,M;
  while(cin >> N >> M){

    LLI ans = 0;
    LLI c = 1;
    
    FORE(i,1,M){
      (c *= (M-i+1) * mod_inv(i,mod) % mod) %= mod;
      
      LLI t = power(i,N,mod) * c % mod;
      if((M-i)%2) t = -t;
      (ans += t + mod) %= mod;
    }
    
    cout << ans << endl;

  }
  
  return 0;
}