/* -*- coding: utf-8 -*-
 *
 * 391.cc: No.391 CODING WAR - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_M = 100000;

typedef long long ll;
const ll MOD = 1000000007;

/* typedef */

typedef vector<int> vi;
typedef queue<int> qi;
typedef pair<int,int> pii;

/* global variables */

/* subroutines */

ll powmod(ll a, ll n) {  // a^n % MOD
  ll pm = 1;
  while (n > 0) {
    if ((n & 1) != 0) pm = (pm * a) % MOD;
    a = (a * a) % MOD;
    n >>= 1;
  }
  return pm;
}

/* main */

int main() {
  ll n;
  int m;
  cin >> n >> m;

  if (n < m) {
    puts("0");
    return 0;
  }

  ll sum = 0, nck = 1;
  bool plus = true;

  for (int k = 0; k <= m; k++) {
    ll pm = powmod((ll)(m - k), n);
    //printf("k=%d: nck=%lld, pm=%lld\n", k, nck, pm);
    ll t = nck * pm % MOD;
    sum = (sum + (plus ? t : MOD - t)) % MOD;

    nck = nck * (m - k) % MOD * powmod((ll)(k + 1), MOD - 2) % MOD;
    plus = ! plus;
  }

  printf("%lld\n", sum);
  return 0;
}