#include<bits/stdc++.h>
using namespace std;
using LL=long long;
using ULL=unsigned long long;
#define rep(i,n) for(int i=0; i<(n); i++)

int N,K;
int A[100000];
ULL M=0;

int main(){
  scanf("%d%d",&N,&K);
  rep(i,N) scanf("%d",&A[i]);
  rep(i,N) M+=A[i];
  ULL S=0;
  rep(i,N) S=(S*K+A[i])%M;
  printf("%llu\n",S);
  return 0;
}