题解 | #很简单的题。。。。。。#

import java.util.Scanner;
public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int L =sc.nextInt();  int R = sc.nextInt();
        int count = 0;
        for(int i=L; i<=R; i++){
            int j = i;
            while(j != 0){
                if(j%10==2)  //取余看每一位是否等于2
                    count++;
                j = j/10;    //取整数方便下一次取的余数只有一位数
            }
            
        }
        System.out.println(count);
    }
}