Unique String Rearrangements

You are given a string s consisting of lowercase English letters. Your task is to calculate the number of unique rearrangements (permutations) of the characters in s. Two rearrangements are considered different if the order of the letters is different.

Mathematically, if the length of the string is \(n\) and each distinct letter \(i\) appears \(k_i\) times, the number of unique rearrangements is given by:

[ \frac{n!}{\prod_i (k_i)!} ]

For example, for the string "aabb", the result is \(\frac{4!}{2!\times2!} = 6\).

inputFormat

The input consists of a single line containing the string s (only lowercase English letters).

outputFormat

Output a single integer which represents the number of unique rearrangements of the string s.

abc

6