#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
#define int long long
signed main(){
  int n,k;
  cin>>n>>k;
  int a[n];
  int sum=0;
  int val=0;
  rep(i,n){
    cin>>a[i];
    sum+=a[i];
  }
  rep(i,n){
    val=(val*k+a[i])%sum;
  }
  //cout<<sum<<endl;
  //cout<<val<<endl;
  cout<<val%sum<<endl;
  return 0;
}