#include <bits/stdc++.h>
using namespace std;
#define int long long   // <-----!!!!!!!!!!!!!!!!!!!

#define rep(i,n) for (int i=0;i<(n);i++)
#define rep2(i,a,b) for (int i=(a);i<(b);i++)
#define rrep(i,n) for (int i=(n)-1;i>=0;i--)
#define rrep2(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define all(a) (a).begin(),(a).end()

typedef long long ll;
typedef pair<int, int> Pii;
typedef tuple<int, int, int> TUPLE;
typedef vector<int> V;
typedef vector<V> VV;
typedef vector<VV> VVV;
typedef vector<vector<int>> Graph;
const int inf = 1e9;
const int mod = 1e9 + 7;

ll powmod (ll a, ll p) {
	ll ans = 1;
	ll mul = a;
	for (; p > 0; p >>= 1, mul = (mul * mul) % mod) {
		if ((p & 1) == 1) ans = (ans * mul) % mod;
	}
	return ans;
}

const int MAX_N = 100010;

ll fact[MAX_N];
ll revFact[MAX_N];
// !!!!!!!!SET FACT!!!!!!!
void setFact(int N) {
	fact[0] = 1;
	for (int i = 1; i < N; i++) {
		fact[i] = fact[i - 1] * i;
		fact[i] %= mod;
	}
	revFact[N - 1] = powmod(fact[N - 1], mod - 2);
	for (int i = N - 2; i >= 0; i--) {
		revFact[i] = revFact[i + 1] * (i + 1);
		revFact[i] %= mod;
	}
}

ll getC(int a, int b) {
	return (((fact[a] * revFact[b]) % mod) * revFact[a - b]) % mod;
}

signed main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(0);

	int N, M;
	cin >> N >> M;
	setFact(MAX_N);
	int ans = 0;
	for (int x = M; x > 0; x--) {
		ans += ((M - x) % 2 ? -1 : 1) * getC(M, x) * powmod(x, N);
		ans %= mod;
	}

	cout << (ans + mod) % mod << endl;
}