#include <iostream>
#include <vector>
using namespace std;

const long long MOD = 1000000007;

template <int mod>
struct Combination {
  long long n_max;
  vector<long long> fac, inv, finv;
  Combination(int n):n_max(n), fac(n+1,1), inv(n+1,1), finv(n+1,1){
    for(int i = 2; n > i; i++){
      fac[i] = (fac[i-1]*i)%mod;
      inv[i] = mod-((inv[mod%i]*(mod/i))%mod);
      finv[i] = (finv[i-1]*inv[i])%mod;
    }
  }

  long long C(int n, int r){
    if(n < r)return 0;
    if(n > n_max)return 0;
    return (((fac[n]*finv[r])%mod)*finv[n-r])%mod;
  }

  long long P(int n, int r){
    if(n < r)return 0;
    if(n > n_max)return 0;
    return (fac[n]*finv[n-r])%mod;
  }

  long long H(int n, int r){
    if(n==0 && r==0)return 1;
    return C(n+r-1, r);
  }
};
using comb = Combination<MOD>;

template <typename T>
T uPow(T z,T n, T mod){
  T ans = 1;
  while(n != 0){
    if(n%2){
      ans*=z;
      if(mod)ans%=mod;
    }
    n >>= 1;
    z*=z;
    if(mod)z%=mod;
  }
  return ans;
}

int main(){
  long long n,m;cin>>n>>m;
  comb c(m+1);
  int sign = (m%2 == 0 ? 1 : -1);
  long long ans = 0;
  for(long long i = 0; m >= i; i++){
    long long tmp = (c.C(m,i)*uPow(i,n,MOD))%MOD;
    if(sign == -1)tmp = MOD - tmp;
    ans = (ans + tmp)%MOD;
    sign *= -1;
  }
  cout << ans << endl;
}