#include <bits/stdc++.h>   using namespace std;   int main() {     int n;     cin >> n;     int biceps = 0, back = 0, chest = 0;     for (int i = 0; i < n; i++) {       int a;       cin >> a;       if (i % 3 == 0) chest += a;       if (i % 3 == 1) biceps += a;       if (i % 3 == 2) back += a;     }     if (chest > back && chest > biceps) cout <<  chest ;     if (back > chest && back > biceps) cout <<  back ;     if (biceps > chest && biceps > back) cout <<  biceps ;     return 0;   }   