#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < (n);i++)
#define sz(x) int(x.size())
typedef long long ll;
typedef long double ld;
typedef pair<int,int> P;
typedef pair<ll, int> PL;
constexpr int mod = 1e9 + 7;
int main() {
  int p, k;
  cin >> p >> k;
  vector<ll> dp(2, 0);
  dp[0] = 1;

  for (int i = 0; i < k; i++) {
    vector<ll> ndp(2, 0);
    ndp[0] = dp[0] + dp[1];
    ndp[0] %= mod;
    ndp[1] = (dp[0] + dp[1]) % mod;
    (ndp[1] *= (p - 1)) %= mod;
    (ndp[0] += (dp[0] * p % mod + dp[1]) % mod) %= mod;
    (ndp[1] += (dp[1] * (p - 1) % mod)) %= mod;
    swap(dp, ndp);
  }
  cout << dp[0] << endl;
  return 0;
}