#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <algorithm>
#include <vector>
#include <math.h>
#include <iomanip>
#include <stack>
#include <queue>
#include <set>
#include <map>

using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using pint = pair<int , int>;

//const ll mod = 1000000007;
const ll mod = 998244353;
const ld pi = 3.14159265358979;

long long gcd(long long a,long long b){
  if(a < b)swap(a , b);
  if(a == 0 || b == 0)return a;
  if(a % b == 0)return b;
  else return gcd(b , a%b);
}

int main() {
  //ios::sync_with_stdio(false);
  //cin.tie(0);
  //cout << fixed << setprecision(15);
  int n , k;
  cin >> n >> k;
  vector<int> a(n);
  ll sum = 0;
  for(int i = 0; i < n; i++){
  	cin >> a[i];
  	sum += a[i];
  }
  
  reverse(a.begin() , a.end());
  ll ans = 0;
  ll kk = 1;
  for(int i = 0; i < n; i++){
  	if(i >= 1)kk *= k;
  	kk %= sum;
  	ans += kk * a[i];
  	ans %= sum;
  }
  cout << ans << endl;
  return 0;
}