#include<stdio.h>
#include<stdlib.h>
typedef struct node{
    int data;
}nd;
int main(){
    int n,L;
    int a[n];
    scanf("%d",&n);
    if(n<0){
        printf("Invalid input");
    }
    for(int i=0;i<n;i++){
      scanf("%d",&L);
    }
    int count=0;
    int level=0;
    int node=0;
    int reached=0;
    for(int i=0;i<n;i++){
        if(level==L){
            sum+=a[i];
            reached=1;
        }
        count++;
        if(count++==node){
            level++;
            node*=2
            count=0;
            if(reached)
        }
        
    }
    scanf("%d",&L);
}