Leftrightarrow

题目描述

You are given a string $S$ consisting of <, $=$, and >.
确定字符串 $S$ 是否为一个 双向箭头 字符串。
当且仅当存在正整数 $k$ 使得 $S$ 是由一个 <、$k$ 个 $=$ 和一个 > 按此顺序拼接而成且长度为 $(k+2)$ 时，$S$ 才是双向箭头字符串。

输入格式

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

输出格式

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

Yes

==>

No

>

No

提示

$S$ is a string of length between $3$ and $100$, inclusive, consisting of <, $=$, and >.<====> is a concatenation of one <, four $=$s, and one >, in this order, so it is a bidirectional arrow string.
Hence, print $Yes$.
==> does not meet the condition for a bidirectional arrow string.
Hence, print $No$.

标签: AtCoder|abc345A

来源

AtCoder|abc345A