#include <bits/stdc++.h>
using namespace std;
const int MOD = int(1e9) + 7;
const int INF = 0x3f3f3f3f;
const double EPS = 1e-9;
const double PI = acos(-1.0);
const int maxn = 2000001;
int n;
int main() {
  int n;
  while (cin >> n) {
    int k, sum1 = 0, sum2 = 0, sum3 = 0, flag = 1;
    for (int i = 1; i <= n; i++) {
      cin >> k;
      if (flag == 3) {
        sum3 += k;
        flag = 1;
      } else if (flag == 2) {
        sum2 += k;
        flag++;
      } else {
        sum1 += k;
        flag++;
      }
    }
    int ans = max(sum1, sum2);
    ans = max(ans, sum3);
    if (ans == sum1)
      cout << "chest" << endl;
    else if (ans == sum2)
      cout << "biceps" << endl;
    else
      cout << "back" << endl;
  }
  return 0;
}
