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