题解 | #字符个数统计#

import java.util.*;

public class Main {

public static void main(String args[]){
    Scanner sc = new Scanner(System.in);
    
    Set<Character> set = new HashSet<>();
    String str = sc.next();
    int index = str.indexOf("/\n");
    if(index>-1){
        str = str.substring(0, index);
    }
    
    for(int i=0;i<str.length();i++) {
    	set.add(str.charAt(i));
    }
    
    System.out.print(set.size());
    
}

}