Good String Transformation

You are given a string S consisting only of the characters 'A' and 'B'. You are allowed to perform an operation that removes one character from any pair of consecutive identical characters. A string is called good if it does not contain two consecutive 'A's or two consecutive 'B's, i.e. it is strictly alternating.

It can be proven that S can be transformed into a good string by a sequence of such operations if and only if S does not contain the substring AAA or BBB. Your task is to determine whether it is possible to transform the given string into a good string.

Note: The allowed operation is to remove one character from any adjacent identical pair.

inputFormat

The input consists of a single line containing the string S which only contains the characters 'A' and 'B'.

outputFormat

Output a single line containing YES if it is possible to transform S into a good string using the described operations, or NO otherwise.

AABBAA

YES