#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vll = vector<ll>;
using vvll = vector<vll>;
using vvvll = vector<vvll>;
using vvvvll = vector<vvvll>;
using vb = vector<bool>;
using vvb = vector<vb>;
using vvvb = vector<vvb>;
using vvvvb = vector<vvvb>;
using vd = vector<double>;
using vvd = vector<vd>;
using vvvd = vector<vvd>;
#define all(A) A.begin(),A.end()
#define ALL(A) A.begin(),A.end()
#define rep(i, n) for (ll i = 0; i < (ll) (n); i++)
using pqr = priority_queue<pair<ll, ll>, vector<pair<ll, ll>>, greater<pair<ll, ll>>>;

template<class T>
bool chmax(T& p, T q, bool C = 1) {
    if (C == 0 && p == q) {
        return 1;
    }
    if (p < q) {
        p = q;
        return 1;
    }
    else {
        return 0;
    }
}

template<class T>
bool chmin(T& p, T q, bool C = 1) {
    if (C == 0 && p == q) {
        return 1;
    }
    if (p > q) {
        p = q;
        return 1;
    }
    else {
        return 0;
    }
}

ll gcd(ll(a), ll(b)) {
    if (b == 0)return a;
    ll c = a;
    while (a % b != 0) {
        c = a % b;
        a = b;
        b = c;
    }
    return b;
}

ll modPow(long long a, long long n, long long p = 1e9 + 7) {
    if (n == 0) return 1; // 0乗にも対応する場合
    if (n == 1) return a % p;
    if (n % 2 == 1) return (a * modPow(a, n - 1, p)) % p;
    long long t = modPow(a, n / 2, p);
    return (t * t) % p;
}



vector<ll> fact, factinv, inv;
ll mod = 1e9 + 7;
void prenCkModp(ll n) {
    fact.resize(n + 5);
    factinv.resize(n + 5);
    inv.resize(n + 5);
    fact.at(0) = fact.at(1) = 1;
    factinv.at(0) = factinv.at(1) = 1;
    inv.at(1) = 1;
    for (ll i = 2; i < n + 5; i++) {
        fact.at(i) = (fact.at(i - 1) * i) % mod;
        inv.at(i) = mod - (inv.at(mod % i) * (mod / i)) % mod;
        factinv.at(i) = (factinv.at(i - 1) * inv.at(i)) % mod;
    }

}
ll nCk(ll n, ll k) {
    if (n < k) return 0;
    return fact.at(n) * (factinv.at(k) * factinv.at(n - k) % mod) % mod;
}

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);


    ll N, M;
    cin >> N >> M;
    prenCkModp(100000);
    ll an = 0;
    for (ll m = M; m > 0; m--) {
        ll p = 1;
        if ((M - m) % 2 != 0)p *= -1;
        ll q = modPow(m, N);
        ll r = nCk(M, m);
        //cout << p << " " << q << " " << r << endl;
        an += p * (q * r) % mod;
        an %= mod;
        an += mod;
        //cout << an % mod << endl;
    }
    //cout<<inv[3]<<endl;
    //cout << nCk(4, 4) << endl;
    cout << an % mod << endl;
}