#include<bits/stdc++.h>
#define int long long
using namespace std;
int N,K,A[1<<20],sum,ans;
signed main(){
    cin>>N>>K;
    for(int i=0;i<N;i++)cin>>A[i],sum+=A[i];
    for(int i=0;i<N;i++)ans=(ans*K+A[i])%sum;
    cout<<ans<<endl;
}