#define _USE_MATH_DEFINES
#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <complex>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
#include <iterator>
using namespace std;

const int MOD = 1000000007;

long long extgcd(long long a, long long b, long long &x, long long &y) {
    long long g = a;
    if(b != 0){
        g = extgcd(b, a % b, y, x);
        y -= (a / b) * x;
    }else{
        x = 1;
        y = 0;
    }
    return g;
}

long long mod_inverse(long long a, long long m)
{
    long long x, y;
    extgcd(a, m, x, y);
    return (x % m + m) % m;
}

class FactorialCalculation
{
private:
    const int mod;
    vector<long long> factorial;
    vector<long long> invFactorial;
public:
    FactorialCalculation(int n, int mod) : mod(mod)
    {
        factorial.resize(n+1, 1);
        invFactorial.resize(n+1, 1);
        for(int i=1; i<=n; ++i){
            factorial[i] = factorial[i-1] * i % mod;
            invFactorial[i] = mod_inverse(factorial[i], mod);
        }
    }
    long long getFactorial(int n){
        return factorial[n];
    }
    long long getPermutation(int n, int r){
        if(n < r)
            return 0;
        return factorial[n] * invFactorial[n-r] % mod;
    }
    long long getCombination(int n, int r){
        if(n < r)
            return 0;
        return getPermutation(n, r) * invFactorial[r] % mod;
    }
    long long getHomogeneous(int n, int r){
        return getCombination(n+r-1, r);
    }
};

long long power(long long a, long long b)
{
    long long ret = 1;
    long long tmp = a % MOD;
    while(b > 0){
        if(b & 1){
            ret *= tmp;
            ret %= MOD;
        }
        tmp *= tmp;
        tmp %= MOD;
        b >>= 1;
    }
    return ret;
}

int main()
{
    long long n;
    int m;
    cin >> n >> m;

    FactorialCalculation fc(m, MOD);

    long long ans = 0;
    for(int i=m; i>=1; --i){
        if((m - i) % 2 == 0){
            ans += fc.getCombination(m, i) * power(i, n);
            ans %= MOD;
        }
        else{
            ans -= fc.getCombination(m, i) * power(i, n);
            ans %= MOD;
            ans += MOD;
            ans %= MOD;
        }
    }
    cout << ans << endl;

    return 0;
}