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

using ll = long long;
const ll MOD = 1e9 + 7;

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  
  ll p, k;
  cin >> p >> k;
  
  vector<vector<ll>> x(k + 1, vector<ll>(2, 0));
  x.at(0).at(0) = 1;
  for (int i = 0; i < k; i++) {
    // add
    x.at(i + 1).at(0) += x.at(i).at(0) + x.at(i).at(1);
    x.at(i + 1).at(1) += (x.at(i).at(0) + x.at(i).at(1)) * (p - 1);
    // multiple
    x.at(i + 1).at(0) += x.at(i).at(0) * p + x.at(i).at(1);
    x.at(i + 1).at(1) += x.at(i).at(1) * (p - 1);
    
    x.at(i + 1).at(0) %= MOD;
    x.at(i + 1).at(1) %= MOD;
  }
  
  cout << x.at(k).at(0) << '\n';
}