#include <bits/stdc++.h>
#include <atcoder/all>
using mint = atcoder::modint1000000007;
using namespace std;

int main() {
	int n, m;
	cin >> n >> m;
	vector<mint> fact = {1};
	for (int i = 1; i < 1010101; i++){
		fact.push_back(fact.back() * mint(i));
	}
	auto cmb = [&](int n,int r){
		return fact[n] / fact[n - r] / fact[r];
	};
	mint ans = 0;
	for (int i = 0; i <= m; i++){
		ans += mint(-1).pow(m - i) * cmb(m, i) * mint(i).pow(n);
	}
	cout << ans.val() << endl;
}