public Contest156A() {
    Scanner in = new Scanner(System.in);

    int num = in.nextInt();
    int[] totals = new int[3];
    for (int x = 0; x < num; x++) {
      totals[x % 3] += in.nextInt();
    }

    int max = 0;
    String muscle;
    max = Math.max(max, totals[0]);
    max = Math.max(max, totals[1]);
    max = Math.max(max, totals[2]);

    if (max == totals[0])
      muscle = "chest";
    else if (max == totals[1])
      muscle = "biceps";
    else
      muscle = "back";

    System.out.println(muscle);
  }