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

int main(){
  ll n, k; cin >> n >> k;
  vector<ll> a(n);
  for(int i = 0; i < n; i++) cin >> a[i];
  ll digit = 0;
  for(int i = 0; i < n; i++) digit += a[i];
  ll ans = 0;
  ll pow = 1;
  for(int i = 0; i < n; i++){
    ans += (pow*a[n-1-i])%digit;
    ans %= digit;
    pow *= k;
  }
  ans = (ans+digit)%digit;
  cout << ans << endl;
  return 0;
}