In PHP:

print count(array_unique(str_split($s))) . "\n";

I think just about everyone figured out that the question meant to simply ask for the number of unique characters in a given string.

JAVA8 SOLUTION:

import java.io.; import java.util.; import java.text.; import java.math.; import java.util.regex.*;

public class Solution {

public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    int n = in.nextInt();
    for(int a0 = 0; a0 < n; a0++){
        String s = in.next();
        System.out.println(s.chars().distinct().count());
    }
}

}

Just the length of the set of characters in the given string. Only need to add one line in python.

@WatchandLearn

Instead of adding each char to the set and letting the set look through itself to determine if the char has already been added to it (which may be a O(n) operation), you could just do the check yourself. I did it using an array of booleans of size 26. When I see the character, I set the bool value to true (looking up using the letters ASCII value). This is a O(1) operation. This makes the solution O(n) because we only look through each character one time.

In Python:

for i in range( int( input() ) ):
    print(len(set(input())))