#include <bits/stdc++.h>
using namespace std;
using ll=long long;
#define MOD 998244353
using Graph=vector<vector<pair<int,int>>>;

int main(){
  int N;
  ll K;
  cin>>N>>K;
  vector<ll> A(N);
  for(int i=0;i<N;i++){
    cin>>A[i];
  }

  ll sum=0;
  for(int i=0;i<N;i++){
    sum+=A[i];
  }
  ll ans=0;
  ll res=1;
  for(int i=N-1;i>=0;i--){
    ans+=A[i]*res;
    ans%=sum;
    res=res*K%sum;
  }
  cout<<ans<<endl;
}