#include <bits/stdc++.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using ll = long long;
using mint = atcoder::modint998244353;
using maxt = atcoder::modint1000000007;

int main() {
	int N, K;
	cin >> N >> K;
	vector<int> A(N);
	ll sum = 0;
	for(int &o : A) {
	  cin >> o;
	  sum += o;
	}
  ll a = 0;
  ll tmp = 1;
	for(int i = N - 1; i >= 0; i--) {
	  a += A.at(i) * tmp;
	  tmp *= K;
	}
	cout << a % sum << endl;
}