103450: [Atcoder]ABC345 A - Leftrightarrow
Memory Limit：256 MB
Time Limit：2 S
Judge Style：Text Compare
Creator：
Submit：12
Solved：0
Description
Scoring: $100$ points
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
Input
Output
评分：100分
部分
问题说明
你将得到一个由`<`、`=`和`>`组成的字符串$S$。
确定$S$是否为双向箭头字符串。
如果存在一个正整数$k$，使得$S$是按此顺序由一个`<`、$k$个`=`和一个`>`组成的字符串，长度为$(k+2)$，则称$S$为双向箭头字符串。
部分
约束
* $S$是一个长度在3到100之间的字符串，由`<`、`=`和`>`组成。
输入输出格式
输入
输入按以下格式从标准输入给出：
$S$
输出
如果$S$是双向箭头字符串，输出`Yes`；否则，输出`No`。
样例输入1
`<====>`