#include <bits/stdc++.h>
#define NIL (-1)
#define ll long long
using namespace std;
const double PI = acos(-1.0);

int main() {
	ll N, K;
	cin >> N >> K;

	ll n = 0LL, c = 1;
	ll s = 0;
	vector<int> A(N);
	for (int i = 0; i < N; i++) {
		cin >> A[i];
		s += A[i];
	}
	reverse(A.begin(),A.end());
	for (int i = 0; i < N; i++) {
		n += A[i] * c;
		n %= s;
		c *= K;
		c %= s;
	}
	cout << n%s << endl;

	return 0;
}