import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
while (scanner.hasNext()) {
String nextLine = scanner.nextLine();
char[] charArray = nextLine.toCharArray();
HashSet<Character> set = new HashSet<>();
for (int i = 0; i < charArray.length; i++) {
set.add(charArray[i]);
}
System.out.println(set.size());
}
}
}
import java.util.HashSet;
import java.util.List;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
while (scanner.hasNext()) {
String nextLine = scanner.nextLine();
char[] charArray = nextLine.toCharArray();
HashSet<Character> set = new HashSet<>();
for (int i = 0; i < charArray.length; i++) {
set.add(charArray[i]);
}
System.out.println(set.size());
}
}
}