/* -*- coding: utf-8 -*-
 *
 * 1518.cc:  No.1518 Simple Combinatorics - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MOD = 1000000007;

/* typedef */

typedef long long ll;

/* global variables */

int powmod(int a, int n) {  // a^n % MOD
  int pm = 1;
  while (n > 0) {
    if (n & 1) pm = (ll)pm * a % MOD;
    a = (ll)a * a % MOD;
    n >>= 1;
  }
  return pm;
}

/* subroutines */

/* main */

int main() {
  int n, k;
  scanf("%d%d", &n, &k);

  int a = powmod(n, k);
  int b = powmod(n - 1, k);
  int c = (ll)n * (a + MOD - b) % MOD;
  printf("%d\n", c);
  return 0;
}