#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
   int n,k,i,j,a[i],cost=0;
    cin>>n>>k;
    for(i=0;i<n;i++) cin>>a[i];
    sort(a,a+n);
    for(i=0,j=n/2;j>0;i++,j/=2)
        {
          cost+=a[j];
       }
    cout<<cost;
    
    return 0;
}