#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint1000000007;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000001

int main(){
	
	int N,K;
	cin>>N>>K;
	
	mint ans = 1;
	mint t = N-1;
	t /= N;
	t = mint(t).pow(K);
	t *= -1;
	
	ans += t;
	
	ans *= N;
	
	ans *= mint(N).pow(K);
	
	cout<<ans.val()<<endl;
	
	return 0;
}