#include <bits/stdc++.h>
#define int long long
using namespace std;
 
signed main() {
    int N,K;cin>>N>>K;int H=0;
    vector<int>V(N);
    for(int X=0;X<N;X++){
        cin>>V[X];H+=V[X];
    }
    reverse(V.begin(),V.end());
    int U=1;
    int S=0;
    for(int X=0;X<N;X++){
        U%=H;V[X]%=H;S+=(U*V[X])%H;S%=H;
        U*=K;
    }
    cout<<S<<endl;
}