Scoring: $100$ points

问题陈述

给定一个由 <、= 和 > 组成的字符串 $S$。 判断 $S$ 是否是一个 双向箭头 字符串。 一个字符串 $S$ 是双向箭头字符串当且仅当存在一个正整数 $k$，使得 $S$ 是按照这个顺序连接一个 <、$k$ 个 = 和一个 >，长度为 $(k+2)$。

以上为大语言模型 kimi 翻译，仅供参考。

Problem Statement

You are given a string $S$ consisting of <, =, and >.
Determine whether $S$ is a bidirectional arrow string.
A string $S$ is a bidirectional arrow string if and only if there is a positive integer $k$ such that $S$ is a concatenation of one <, $k$ =s, and one >, in this order, with a length of $(k+2)$.

Constraints

• $S$ is a string of length between $3$ and $100$, inclusive, consisting of <, =, and >.

Input

The input is given from Standard Input in the following format:

$S$

Output

If $S$ is a bidirectional arrow string, print Yes; otherwise, print No.

Sample Input 1

<====>

Sample Output 1

Yes

<====> is a concatenation of one <, four =s, and one >, in this order, so it is a bidirectional arrow string.
Hence, print Yes.

Sample Input 2

\==>

Sample Output 2

No

==> does not meet the condition for a bidirectional arrow string.
Hence, print No.

Sample Input 3

<>>

Sample Output 3

No

update @ 2024/5/16 17:16:35