#include <bits/stdc++.h>
using namespace std;
using ll = long long;
constexpr long long MOD = 1000000007;
long long power(long long x,long long n){
    long long res = 1;
    while(n > 0) {
        if(n & 1) res *= x;
        x *= x;
        n>>=1;
    }
    return res;
}
int main(){
    ll p, k;
    cin >> p >> k;
    ll dp[k + 1];
    for (ll i = 0; i < k + 1; i++) dp[i] = 0;
        dp[0] = 1;
    for (ll i = 0; i < k; i++) {
        dp[i + 1] = dp[i] * p;//掛け算のとき
        dp[i + 1] += power(p, i);
        dp[i + 1] %= MOD;
    }
    cout << dp[k] << endl;
}