xy-Balanced String

Background

Dawei and Xiaoxiao are studying string properties. They have defined a special type of string balance.

Problem Description

We'll say that a String is xy-balanced if for all the 'x' chars in the string, there exists a 'y' char somewhere later in the string. So "xxy" is balanced, but "xyx" is not. One 'y' can balance multiple 'x's. Return true if the given string is xy-balanced.

Input Format

Input is given from standard input in the following format.

s

Output Format

Output is printed to standard output in the following format.

true or false

Sample

aaxbby

true

aaxbb

false

yaaxbb

false

Sample Explanation

For Sample 1, the string is "aaxbby". The last 'y' is at index 5. There are no 'x's after it, so it is xy-balanced. For Sample 2, the string is "aaxbb". There are no 'y's in the string, but there are 'x's, so it is not xy-balanced. For Sample 3, the string is "yaaxbb". The last 'y' is at index 0. There are 'x's after it (at indices 2 and 3), so it is not xy-balanced.

Constraints

Time limit: 1s, Memory limit: 1024KiB for each test case.