递推

#include <bits/stdc++.h>
using namespace std;
const int N = 100010;
int w[N];
int main(){
    int n;
    cin>>n;
    for(int i=1;i<=n;i++){
        scanf("%d",&w[i]);
    }
    double E;
    for(int i=n;i>0;i--){
        E = (w[i]+E)/2;
    }
    E = ceil(E);
    cout<<E<<endl;
}