Maximum Removal for Even Frequencies

Given a string s, determine the maximum number of characters you can remove such that the frequency of each remaining character is even. Formally, for every character c that appears in the remaining string, the number of occurrences of c is even.

Input: A single string s provided via standard input.

Output: A single integer representing the maximum number of characters that can be removed so that each remaining character appears an even number of times.

Note: If the string is empty, simply output 0.

The solution leverages the observation that for each character with an odd frequency, you can remove one occurrence to make it even.

inputFormat

The input consists of a single line containing the string s. The string may contain any printable characters. If the input is empty, consider it as an empty string.

outputFormat

Output a single integer representing the maximum number of characters that can be removed so that every character in the remaining string has an even count.

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