Minimum Deletions to Limit Letter Frequency

You are given a string s consisting of lowercase letters. Your task is to determine the minimum number of deletions required so that every letter appears at most twice in the string.

If a letter appears more than twice, you must remove enough occurrences of that letter so that its total count is reduced to 2.

For example, if s is "aaabbbc", then deleting one 'a' and one 'b' will result in "aabbc", where each letter appears at most twice, so the answer is 2.

Input Constraints: The string length is at least 0 and at most 10⁵ characters.

Note: The input is provided via standard input (stdin) and the output should be printed to standard output (stdout).

inputFormat

The input consists of a single line containing the string s.

Example:

aaabbbc

outputFormat

Output a single integer representing the minimum number of deletions required to ensure that every letter in the string appears at most twice.

Example:

2

## sample

aaabbbc

2