#include<iostream>
#include<set>
#include<algorithm>
#include<vector>
#include<string>
#include<set>
#include<map>
#include<numeric>
#include<queue>
#include<cmath>
using namespace std;
typedef long long ll;
const ll INF=1LL<<60;
typedef pair<ll,ll> P;
typedef pair<int,P> PP;
const ll MOD=1e9+7;

ll mod_pow(ll x,ll y,ll mod){
    ll res=1;
    while(y>0){
        if(y&1){
            res*=x;
            res%=mod;
        }
        x*=x;
        x%=mod;
        y/=2;
    }

    return res;
}

int main(){
    ll N,K;
    cin>>N>>K;
       

    ll ans=(mod_pow(N,K,MOD) - mod_pow(N-1,K,MOD)+MOD)%MOD;
    ans*=N;
    ans%=MOD;

    cout<<ans<<endl;
}