#include <bits/stdc++.h>

using namespace std;

using ll = long long;

constexpr int MAXV = 100000;

ll f[MAXV + 1], fi[MAXV + 1];

constexpr ll MOD = 1000000007;

ll modpow(ll x, ll n, ll mod = MOD) {
    ll res = 1;
    while (n > 0) {
        if (n & 1) res = res * x % mod;
        x = x * x % mod;
        n >>= 1;
    }
    return res;
}

ll comb(int r, int c) {
    if (r < c) return 0;
    return f[r] * fi[c] % MOD * fi[r - c] % MOD;
}

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    
    f[0] = 1;
    for (int i = 1; i <= MAXV; ++i) {
        f[i] = f[i - 1] * i % MOD;
    }

    fi[MAXV] = modpow(f[MAXV], MOD - 2);
    for (int i = MAXV; i > 0; --i) {
        fi[i - 1] = fi[i] * i % MOD;
    }

    int n, m;
    cin >> n >> m;
    
    ll ans = 0;
    for (int i = 0; i <= m; ++i) {
        ll tmp = comb(m, i) * modpow(i, n) % MOD;
        if ((m - i) % 2 == 0) ans += tmp;
        else ans += MOD - tmp;
        ans %= MOD;
    }
    cout << ans << "\n";
    return 0;
}