#include <iostream>
#include <algorithm>
#include <vector>
#include <map>
using namespace std;
typedef long long ll;
map<pair<ll, ll>, ll> cmb;
int64_t ans;

const int64_t MOD = 1e9+7;
void add(int64_t& a, int64_t b){
    a = (a+b) % MOD;
}
void mul(int64_t& a, int64_t b){
    a = a*b % MOD;
}
 
vector<int64_t> fact, seq_inv, fact_inv;
 
void create_fact_mod(int num){
    fact[0] = fact[1] = 1;
    for(int i=2; i<=num; i++) fact[i] = fact[i-1] * i % MOD;
}
 
void create_seq_inv_mod(int num){
    seq_inv[0] = seq_inv[1] = 1;
    for(int i=2; i<=num; i++) seq_inv[i] = (MOD - MOD/i) * seq_inv[MOD%i] % MOD;
}
 
void create_fact_inv_mod(int num){
    fact_inv[0] = fact_inv[1] = 1;
    for(int i=2; i<=num; i++) fact_inv[i] = fact_inv[i-1] * seq_inv[i] % MOD;
}
 
void create_mod_tables(int num){
    fact.resize(num+1);
    seq_inv.resize(num+1);
    fact_inv.resize(num+1);
    create_fact_mod(num);
    create_seq_inv_mod(num);
    create_fact_inv_mod(num);
}
 
int64_t comb_mod(int n, int k){
    return fact[n] * fact_inv[n-k] % MOD * fact_inv[k] % MOD;
}
 
int64_t perm_mod(int n, int k){
    return fact[n] * fact_inv[n-k] % MOD;
}
 
int64_t power_mod(int64_t num, int64_t power){
    int64_t prod = 1;
    num %= MOD;
    while(power > 0){
        if(power&1) prod = prod * num % MOD;
        num = num * num % MOD;
        power >>= 1;
    }
    return prod;
}
 
int64_t extgcd(int64_t a, int64_t b, int64_t& x, int64_t& y){
    int64_t d = a;
    if(b != 0){
        d = extgcd(b, a%b, y, x);
        y -= (a/b) * x;
    }else{
        x = 1; y = 0;
    }
    return d;
}
 
int64_t inv_mod(int64_t a){
    int64_t x, y;
    extgcd(a, MOD, x, y);
    return (MOD + x%MOD) % MOD;
}
 

int main()
{
    int n, m;
    cin >> n >> m;
    ans = power_mod(m, n);
    create_mod_tables(200000);
    int k = -1;
    for (int j = 1; j < m; ++j) {
        int64_t xs = 1;
        mul(xs, k);
        add(xs, MOD);
        mul(xs, power_mod(j, n));
        add(xs, MOD);
        mul(xs, comb_mod(m, j));
        add(xs, MOD);
        add(ans, xs);
        add(ans, MOD);
        k *= -1;
    }
    cout << ans << endl;
    return 0;
}