#include <bits/stdc++.h>
#include <atcoder/modint>
using namespace std;
using namespace atcoder;
using ll = long long;
using mint = modint1000000007;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  ll N, P;
  cin >> N >> P;

  if(N == 1) { cout << 0 << "\n"; }
  if(N == 2) { cout << 1 << "\n"; }
  if(N < 3) { return 0; }

  mint S = 1, ans = 1;
  vector<mint> A(N, 0);
  A[1] = 1;
  for(ll i = 2; i < N; i++) {
    A[i] = A[i - 1] * P + A[i - 2];
    S += A[i];
    ans += S * A[i];
  }

  cout << ans.val() << "\n";
}