import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
while(sc.hasNext()) {
String line = sc.nextLine();
char[] chars = line.toCharArray();
Set<Character> set = new HashSet<>();
int count = 0;
for (char aChar : chars) {
if(aChar >= 0 && aChar <= 127 && set.add(aChar) ) {
count++;
}
}
System.out.println(count);
}
}
}