题解 | #字符个数统计#

import java.util.*;

public class Main {
        public static void main(String [] args){
            Scanner scanner = new Scanner(System.in);
            while(scanner.hasNext()){
                String str = scanner.nextLine();
                Set<String> set = new HashSet<>();
                int num = 0;
                for(int i=0; i<str.length(); i++){
                    if(!set.contains(String.valueOf(str.charAt(i)))){
                        set.add(String.valueOf(str.charAt(i)));
                    }
                }
                System.out.print(set.size());
            }
        }
}