Minimum Operations to Empty a String

You are given a string ( s ). In one operation, you can remove all occurrences of any chosen character from the string. Determine the minimum number of operations required to make the string empty. Essentially, if ( D(s) ) denotes the number of distinct characters in ( s ), then the answer is ( D(s) ).

inputFormat

The input consists of a single line containing a non-empty string ( s ) made up of lowercase and/or uppercase letters.

outputFormat

Output a single integer indicating the minimum number of operations required to make the string empty.## sample

aabbcc

3