Longest Subsequence of Distinct Characters

Given a string \(S\), compute the length of the longest subsequence that contains only distinct characters. In other words, if we denote the number of distinct characters in \(S\) as \(D(S)\), then \[ D(S)=|\{ s : s \text{ is in } S \}| \] For example, for the input string "aabbccddeeff" the answer is 6 because there are 6 unique characters: a, b, c, d, e, and f.

Your task is to write a program that reads a string from standard input and outputs the number of distinct characters it contains.

inputFormat

The input consists of a single line containing the string \(S\).\

outputFormat

Print a single integer representing the count of distinct characters in the string \(S\) to standard output.

aabbccddeeff

6