#include <bits/stdc++.h>
using namespace std;
int a[128], n, b[6];
int main() {
  int p = 1;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    b[p] += a[i];
    if (p == 1)
      p = 2;
    else if (p == 2)
      p = 3;
    else if (p == 3)
      p = 1;
  }
  int mx = 0;
  for (int i = 1; i <= 3; i++)
    if (b[i] > mx) {
      mx = b[i];
      p = i;
    }
  if (p == 1) cout << "chest\n";
  if (p == 2) cout << "biceps\n";
  if (p == 3) cout << "back\n";
  return 0;
}
