#include<bits/stdc++.h>
using namespace std;
const int MOD = 1e9 + 7;

long long mod_pow(long long a,long long b,long long mod)
{
  if( b == 0 ) return 1;
  long long res = mod_pow(a*a%mod,b/2,mod);
  if( b&1 ) res = (res * a)%mod;
  return res;
} 
long long inv(long long a,long long mod)
{
  return mod_pow(a, mod - 2, mod);
}

int main()
{
  long long N, K;
  cin >> N >> K;
  long long ret = 0;
  long long comb = 1, poyo = K;
  for(int i = 1; i <= K; i++) {
    long long sign = pow(-1, K - i);
    comb *= poyo--;
    comb %= MOD;
    comb *= inv(i, MOD);
    comb %= MOD;
    (ret += sign * comb * mod_pow(i, N, MOD) + MOD) %= MOD;
  }
  cout << ret << endl;
}