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