#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ld = long double;

int N, K, A[101010], powK[101010];
ll sum, ans;

int main() {
  cin >> N >> K;
  for (int i = N; i >= 1; i--) {
    cin >> A[i];
    sum += A[i];
  }
  powK[1] = 1;
  for (int i = 2; i <= N; i++) {
    powK[i] = (powK[i - 1] * K) % sum; 
  }

  for (int i = 1; i <= N; i++) {
    ans = (ans + (A[i] * powK[i]) % sum) % sum;
  }
  cout << ans << endl;
  return 0;
}