#include<bits/stdc++.h>
using namespace std;

int main(){
    int n; cin>>n;
    vector<int> a(200); fill(a.begin(), a.end(), 0);
    for(int i=0;i<n;i++) cin>>a[i];

    int ans = 1e5;
    for(int i=1;i<=100;i++){
            int add = 0, sub = 0;
            for(int j=0;j<200;j++){
                if(max(i-abs(j-i+1), 0)<a[j]) sub += a[j] - max(i-abs(j-i+1), 0);
                else add += max(i-abs(j-i+1), 0) - a[j];
            }

            if(add<=sub) ans = min(ans, sub);
        }

    cout<<ans<<endl;
    return 0;
}