#include <bits/stdc++.h>
using namespace std;

#include <atcoder/modint>
using mint = atcoder::modint1000000007;

int main() {
    int N, K;
    cin >> N >> K;
    mint ans = mint(N) * (mint(N).pow(K) - mint(N-1).pow(K));
    cout << ans.val() << endl;
}