#include <bits/stdc++.h>
using namespace std;
#define REP(i, n) FOR(i, 0, (n))
#define FOR(i, a, b) for(int i=(a); i<(b); i++)
#define LAR(a, b) ((a)=max((a),(b)))
#define SML(a, b) ((a)=min((a),(b)))
using ll = long long;
using ld = long double;
using vi = vector<int>;
using vl = vector<ll>;
using pii = pair<int, int>;
using vpii = vector<pair<int, int>>;
template<typename T>
using pque = priority_queue<T, vector<T>, greater<T>>;
#define PB push_back
#define EB emplace_back
#define MP make_pair
#define ALL(a) (a).begin(), (a).end()
#ifdef LOCAL_DEBUG
#define DEBUG(...) printf(__VA_ARGS__)
#else
#define DEBUG(...)
#endif

constexpr ll MOD = 1'000'000'007;
ll pw(ll a, ll b){
	ll c = 1;
	do{
		if(b%2) c = c * a % MOD;
		a = a*a % MOD;
	}while(b/=2);
	return c;
}
ll inv(ll a){
	return pw(a, MOD-2);
}

#define N 112345
ll fct[N] = {1}, fctinv[N];
ll cmb(ll a, ll b){
	return fct[a] * fctinv[b] % MOD * fctinv[a-b] % MOD;
}

int main(){
	FOR(i, 1, N) fct[i] = fct[i-1] * i % MOD;
	REP(i, N) fctinv[i] = inv(fct[i]);
	ll m, n; scanf("%lld%lld", &n, &m);
	ll ans = 0;
	for(ll i = m; i >= 1; i--){
		// DEBUG("%lld %lld\n", cmb(m, i), pw(i, n));
		ll fct = cmb(m, i) * pw(i, n) % MOD;
		ans += MOD + ((m-i)%2 ? -1 : 1) * fct;
		ans %= MOD;
	}
	printf("%lld\n", ans);
}