CF980A.Links and Pearls

A necklace can be described as a string of links ('-') and pearls ('o'), with the last link or pearl connected to the first one.

You can remove a link or a pearl and insert it between two other existing links or pearls (or between a link and a pearl) on the necklace. This process can be repeated as many times as you like, but you can't throw away any parts.

Can you make the number of links between every two adjacent pearls equal? Two pearls are considered to be adjacent if there is no other pearl between them.

Note that the final necklace should remain as one circular part of the same length as the initial necklace.

一条项链可以被描述为由链节（‘-’）和珍珠（‘o’）组成的字符串，且最后一个链节或珍珠与第一个链节或珍珠相连。

你可以移除一个链节或一颗珍珠，并将其插入项链上任意两个已存在的链节或珍珠之间（或一个链节与一颗珍珠之间）。该操作可重复执行任意多次，但不允许丢弃任何部分。

你能否使得每两颗相邻珍珠之间的链节数量都相等？若两颗珍珠之间不存在其他珍珠，则称这两颗珍珠相邻。

注意：最终的项链必须仍为一个长度与初始项链相同的环形结构。

The only line of input contains a string $s$ ($3 \leq |s| \leq 100$), representing the necklace, where a dash '-' represents a link and the lowercase English letter 'o' represents a pearl.

输入仅包含一行，为一个字符串 $s$（$3 \leq |s| \leq 100$），表示项链，其中短横线 '-' 表示一个链节，小写英文字母 'o' 表示一颗珍珠。

Print "YES" if the links and pearls can be rejoined such that the number of links between adjacent pearls is equal. Otherwise print "NO".

You can print each letter in any case (upper or lower).

如果可以将链条和珍珠重新连接，使得相邻珍珠之间的链条数量相等，则输出 “YES”；否则输出 “NO”。

你可以以任意大小写（大写或小写）输出每个字母。