#include <iostream>
#include <vector>
#include <cmath>
#include <map>
#include <set>
#include <iomanip>
#include <queue>
#include <algorithm>
#include <numeric>
#include <deque>

using namespace std;
using ll = long long;
const ll modc = 1e9+7;

ll mod_exp(ll b, ll e, ll m=modc){
    if (e > 0 && b == 0) return 0;
    ll ans = 1;
    b %= m;

    while (e > 0){
        if ((e & 1LL)) ans = (ans * b) % m;
        e = e >> 1LL;
        b = (b*b) % m;
    }

    return ans;
}

int main(){
    
    ll N, K, ans;
    cin >> N >> K;
    ans = (modc + mod_exp(N, K) - mod_exp(N-1, K)) % modc;
    ans *= N;
    cout << ans % modc << endl;

    return 0;
}