#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a;i<b;i++)


typedef long long ll;
ll MOD = 1000000007;
const int NUM_FAC = 2000001;
ll modfact(ll x) {
	static ll _fact[NUM_FAC + 1];
	if (_fact[0] == 0) {
		_fact[0] = 1;
		for (int i = 1; i <= NUM_FAC; ++i) _fact[i] = _fact[i - 1] * i%MOD;
	}
	return _fact[x];
}
ll modpow(ll a, ll n) {
	ll r = 1;
	while (n) r = r*((n % 2) ? a : 1) % MOD, a = a*a%MOD, n >>= 1;
	return r;
}
ll moddiv(ll a, ll b)
{
	ll ap_2 = modpow(b, MOD - 2);
	return (a * ap_2) % MOD;
}
ll aCb(ll a, ll b) {
	return moddiv(modfact(a), (modfact(a - b) * modfact(b)) % MOD);
}
//-----------------------------------------------------------------
#define rrep(i,a,b) for(int i=a;i>=b;i--)
ll N, M;
//-----------------------------------------------------------------
int main() {
	cin >> N >> M;

	if (N < M) {
		printf("0\n");
		return 0;
	}

	ll ans = 0;
	int m = 1;
	rrep(i, M, 1) {
		ll t = (aCb(M, i) * modpow(i, N)) % MOD;
		ans += m * t;
		ans = (ans + MOD) % MOD;
		m *= -1;
	}
	cout << ans << endl;
}