编程题：central list

If a list is central symmetry, it is called a central list. for example, 1->3->5->7->9->7->5->3->1 is a central list.
Give you a sequence of numbers, form a link list and then judge whether it is a central list.



### 输入格式:

A sequence of numbers seperated by comma

### 输出格式:

If it is a central list output Yes, otherwise No

### 输入样例:



in
1,3,5,7,9,7,5,3,1,



### 输出样例:



out
Yes








答案：若无答案欢迎评论