#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); i++)
#define rrep(i, n) for (int i = (n - 1); i >= 0; i--)
#define ALL(v) v.begin(), v.end()
using namespace std;
using P = pair<int, int>;
typedef long long ll;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};


long long modpow(long long a, long long n, long long mod) {
    long long res = 1;
    while (n > 0) {
        if (n & 1) res = res * a % mod;
        a = a * a % mod;
        n >>= 1;
    }
    return res;
}

int main() {
  int n, k;
  cin >> n >> k;
  vector<ll> A(n);
  rep(i, n) cin >> A[i];
  ll mod = 0;
  rep(i, n) mod += A[i];
  ll ans = 0;
  reverse(ALL(A));
  rep(i, n){
    ans += modpow(k, i, mod) * A[i];
    ans %= mod;
  }
  cout << ans << endl;
}