#include <bits/stdc++.h>
using namespace std;
#define int long long
typedef pair<int,int> P;
int INF = 3e18+7;
int mod = 1e9+7;
int dx[] = {1, 0,-1, 0, 1, 1,-1,-1};
int dy[] = {0, 1, 0,-1, 1,-1, 1,-1};
signed main() {
    int N,K;
    cin >> N >> K;
    vector<int>A(N);
    int sum = 0;
    for(int i = 0; i < N; i++) {
        cin >> A[i];
        sum += A[i];
    }
    int ans = 0,tmp = 1;
    for(int i = N-1; i >= 0; i--) {
        ans += A[i]*tmp;
        tmp *= K;
        tmp %= sum;
    }
    cout << ans%sum << endl;
}