#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;
using ll = long long;
using ull = unsigned long long;
#define rep(i,n) for(int i=0; i<(n); i++)

const ull M = 1000000007;

ull powm(ull a,ull i){
  if(i == 0) return 1;
  ull r = powm(a*a%M,i/2);
  if(i%2 == 1) r = r * a % M;
  return r;
}

int main(){
  ull N, K; cin >> N >> K;
  ull ans = powm(N,K) * N % M;
  ans = (ans + (M - powm(N-1,K)) * N) % M;
  cout << ans << "\n";
  return 0;
}


struct ios_do_not_sync{
  ios_do_not_sync(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
  }
} ios_do_not_sync_instance;