#include <bits/stdc++.h>
using namespace std;
using ll = long long;
constexpr long long MOD = 1000000007;
int main(){
    ll p, k;
    cin >> p >> k;
    ll dp[k + 1];
    dp[0] = 1;
    for (ll i = 0; i < k + 1; i++) {
        dp[i + 1]+=p;
        dp[i + 1] += dp[i];
        dp[i + 1] %= MOD;
    }
    cout << dp[k] << endl;
}