#include <bits/stdc++.h>
#define be(v) (v).begin(),(v).end()
#define pb(q) push_back(q)
typedef long long ll;
using namespace std;
const ll mod=1000000007, INF=mod*mod*3LL;
#define doublecout(a) cout<<fixed<<setprecision(10)<<a<<endl;

ll fac[200007],finv[200007],inv[200007];
void cominit(){
    fac[0]=fac[1]=1;
    finv[0]=finv[1]=1;
    inv[1]=1;
    for(int i=2;i<200007;i++){
        fac[i]=fac[i-1]*i%mod;
        inv[i]=mod-inv[mod%i]*(mod/i)%mod;
        finv[i]=finv[i-1]*inv[i]%mod;
    }
}
ll com(ll n,ll k){
    if(n<k)return 0;
    if(n<0 || k<0)return 0;
    return fac[n]*(finv[k]*finv[n-k]%mod)%mod;
}
long long modpow(long long a, long long n) {
    long long res = 1;
    while (n > 0) {
        if (n & 1) res = res * a % mod;
        a = a * a % mod;
        n >>= 1;
    }
    return res;
}
int main() {
    cin.tie(0);
    cout.tie(0);
    ios::sync_with_stdio(false);
    cominit();
    ll n, m;
    cin >> n >> m;
    ll ans = 0;
    for(ll i=0;i<=m;i++){
    	ans += ((com(m, i) * modpow(i, n))%mod * (((m-i)&1? -1: 1)))%mod;
    	ans %= mod;
    }
    cout << (ans+mod)%mod << endl;
    return 0;
}