CF 255A - Greg's Workout_世界热门

Greg is a beginner bodybuilder. Today the gym coach gave him the training plan. All it had was n integers a1, a2, ..., an. These numbers mean that Greg needs to do exactly n exercises today. Besides, Greg should repeat the i-th in order exercise ai times.

Greg now only does three types of exercises: "chest" exercises, "biceps" exercises and "back" exercises. Besides, his training is cyclic, that is, the first exercise he does is a "chest" one, the second one is "biceps", the third one is "back", the fourth one is "chest", the fifth one is "biceps", and so on to the n-th exercise.

Now Greg wonders, which muscle will get the most exercise during his training. We know that the exercise Greg repeats the maximum number of times, trains the corresponding muscle the most. Help Greg, determine which muscle will get the most training.

(资料图片仅供参考)

Input

The first line contains integer n (1 ≤ n ≤ 20). The second line contains n integers a1, a2, ..., an (1 ≤ ai ≤ 25) — the number of times Greg repeats the exercises.

Output

Print word "chest" (without the quotes), if the chest gets the most exercise, "biceps" (without the quotes), if the biceps gets the most exercise and print "back" (without the quotes) if the back gets the most exercise.

It is guaranteed that the input is such that the answer to the problem is unambiguous.

Examples

input

2

2 8

output

biceps

input

3

5 1 10

output

back

input

7

3 3 2 7 9 6 8

output

chest

Note

In the first sample Greg does 2 chest, 8 biceps and zero back exercises, so the biceps gets the most exercises.

In the second sample Greg does 5 chest, 1 biceps and 10 back exercises, so the back gets the most exercises.

In the third sample Greg does 18 chest, 12 biceps and 8 back exercises, so the chest gets the most exercise.

中文：

格雷格是一名初学者健美运动员。 今天健身房教练给了他训练计划。 它只有 n 个整数 a1,⟩a2,⟩...,⟩an。 这些数字意味着 Greg 今天刚好需要做 n 次练习。 此外，Greg 应该重复第 i 个，以便练习 ai 次。

格雷格现在只做三种运动：“胸部”运动、“二头肌”运动和“背部”运动。 而且，他的训练是循环的，即第一个动作是“胸”，第二个是“二头肌”，第三个是“背”，第四个是“胸”，第五个是“胸”。 “二头肌”，以此类推到第n个练习。

现在格雷格想知道，在他的训练中，哪块肌肉会得到最多的锻炼。 我们知道格雷格这个动作重复次数最多，对应的肌肉训练最多。 帮助格雷格，确定哪块肌肉将得到最多的训练。

输入

第一行包含整数 n (1 ≤ n ≤ 20)。 第二行包含 n 个整数 a1, a2, ..., an (1 ≤ ai ≤ 25)——Greg 重复练习的次数。

输出

如果胸部得到最多的锻炼，则打印单词“chest”（不带引号）；如果二头肌得到最多的锻炼，则打印“biceps”（不带引号）；如果背部得到锻炼，则打印“back”（不带引号）。 大多数锻炼。

保证输入的问题的答案是明确的。

只要依次去计算每种运动锻炼了多少次即可。