題幹：

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 aitimes.

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

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.

Input

The first line contains integer n

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.

題目大意：

   一個人有n個回合的三個專案要訓練，每個回合ai次，現在告訴你第一個回合先練“chest”，第二個回合練"biceps"，第三個回合練"back"，第四個回合又練“chest”，，以此類推。現在告訴你每個回合的練習次數，問你哪個專案練的次數最多。

解題報告：

  直接暴力，，，注意取模的運用會簡化程式碼，，，但是別忘了要從0開始讀入、、

AC程式碼：

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<queue>
#include<map>
#include<vector>
#include<set>
#include<string>
#include<cmath>
#include<cstring>
#define ll long long
#define pb push_back
#define pm make_pair
#define fi first
#define se second
using namespace std;
const int MAX = 2e6 + 5;
ll n,tmp;
ll bk[20];
int main()
{
	cin>>n;
	for(int i = 0; i<n; i++) {
		scanf("%lld",&tmp);
		bk[i%3]+=tmp;
	}
	if(bk[0] > bk[1] && bk[0] > bk[2]) {
		printf("chest");
	}
	else if(bk[1] > bk[0] && bk[1] > bk[2]) {
		printf("biceps");
	}
	else printf("back");
	return 0 ;
 }

總結：

  一個小坑，，注意一下就好了，，取模的時候，，需要從0開始讀入