题解 | #字符个数统计#

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
      Scanner in = new Scanner(System.in);
      StringBuilder sb1 = new StringBuilder(in.nextLine());
      int counter=0;
      for(int i=0;i<sb1.length();i++){
        for(int j=i+1;j<sb1.length();j++){
            if(sb1.charAt(j)==sb1.charAt(i))    sb1.setCharAt(j,'}');
        }
        if(sb1.charAt(i)>=0&&sb1.charAt(i)<=127&&sb1.charAt(i)!='}') counter++;
      }
      System.out.print(counter);
      in.close();
    }
}