#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <numeric>
#include <functional>
#include <cmath>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <sstream>
#include <string>
#define repd(i,a,b) for (int i=(int)(a);i<(int)(b);i++)
#define rep(i,n) repd(i,0,n)
#define all(x) (x).begin(),(x).end()
#define mod 1000000007
#define inf 2000000007
#define mp make_pair
#define pb push_back
typedef long long ll;
using namespace std;
template <typename T>
inline void output(T a, int p) {
    if(p) cout << fixed << setprecision(p)  << a << "\n";
    else cout << a << "\n";
}
// end of template

const int f = 100001;
vector<ll> fact(f, 1);

ll pow_mod(ll a, ll b, ll m){
    ll ret = 1;
    while (b > 0) {
        if (b & 1) {
            ret = ret * a % m;
        }
        a = a * a % m;
        b >>= 1;
    }
    return ret;
}

ll inv_mod(ll a, ll m){
    return pow_mod(a, m - 2, m);
}

ll comb(ll n, ll k, ll m){
    ll fn = fact[n];
    ll fk = fact[k];
    ll fnk = fact[n - k];
    ll b = inv_mod(fk * fnk % m, m);
    return fn * b % m;
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(0);
    // source code
    
    
    repd(i, 1, f + 1){
        fact[i] = fact[i - 1] * i;
        fact[i] %= mod;
    }
    
    
    ll N, M;
    cin >> N >> M;
    
    if(N < M){
        output(0, 0);
        return 0;
    }
    
    ll ret = 0;
    ll now = M;
    while(now){
        ll c = pow_mod(now, N, mod);
        (c *= comb(M, now, mod)) %= mod;
        if((M - now) % 2 == 1) c *= -1;
//        cout << now << ": " << c << ", " << comb(M, now, mod) <<  endl;
        (ret += c) %= mod;
        now--;
    }
    
    output((ret + mod) % mod, 0);
    
    return 0;
}