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

#define rrep(i,a,b) for(int i=a;i>=b;i--)
typedef long long ll;
ll N, M;
//-----------------------------------------------------------------
ll mo = 1000000007;
ll fact(ll x) {
	const int NUM_ = 400001;
	static ll fac[NUM_ + 1];
	if (fac[0] == 0) {
		fac[0] = 1;
		for (int i = 1; i <= NUM_; ++i) fac[i] = fac[i - 1] * i%mo;
	}
	return fac[x];
}
ll modpow(ll a, ll n) {
	ll r = 1;
	while (n) r = r*((n % 2) ? a : 1) % mo, a = a*a%mo, n >>= 1;
	return r;
}
ll moddiv(ll a, ll b)
{
	ll ap_2 = modpow(b, mo - 2);
	return (a * ap_2) % mo;
}
ll comb(ll a, ll b) {
	ll up = 1;
	rep(i, 0, b) up = (up * a) % mo, a--;
	ll down = 1;
	rep(i, 1, b + 1) down = (down * i) % mo;
	return moddiv(up, down);
}
//-----------------------------------------------------------------
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 = (comb(M, i) * modpow(i, N)) % mo;
		ans += m * t;
		ans = (ans + mo) % mo;
		m *= -1;
	}
	cout << ans << endl;
}