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 next = sc.next();
char[] chars = next.toCharArray();
String str = "";
for (char aChar : chars) {
if(str.indexOf(aChar) == -1){
str = str+aChar;
}
}
System.out.println(str.length());
}
}
}
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 next = sc.next();
char[] chars = next.toCharArray();
String str = "";
for (char aChar : chars) {
if(str.indexOf(aChar) == -1){
str = str+aChar;
}
}
System.out.println(str.length());
}
}
}