#include<bits/stdc++.h>
using namespace std;
using ll = long long int;
using ld = long double;
#define pow(n,m) powl(n,m)
#define sqrt(n) sqrtl(n)
const ll MAX = 5000000000000000000;
const ll MOD = 1000000007;
void randinit(){srand((unsigned)time(NULL));}
ll modpow(ll A,ll B,ll M){
    ll r = 1,p = A;
    while(B > 0){
        if(B % 2 == 1) r = (r * p) % M;
        p = (p * p) % M;
        B /= 2;
    }
    return r;
}
int main(){
    ll N,K;
    cin >> N >> K;
    cout << ((((modpow(N,K,MOD) - modpow(N - 1,K,MOD)) * N) % MOD) + MOD) % MOD << endl;
}