import java.util.Scanner;

/**
 * Created by LBG on 2019/10/26.
 */
public class Main {
    public static void main(String[] args) {
        Scanner cin = new Scanner(System.in);
        int a, b;
        while (cin.hasNext()) {
            a = cin.nextInt();
            b = cin.nextInt();
            int count = 0;
            for (int i = a; i <= b; i++) {
                String num = i + "";
                for (int j = 0; j < num.length(); j++) {
                    if (num.charAt(j) -  Character.valueOf('2') == 0) {
                        count++;
                    }
                }
            }
            System.out.println(count);
        }
    }

}
/**************************************************************
	Problem: 2292
	User: admin
	Language: Java
	Result: Accepted
	Time:4452 ms
	Memory:43260 kb
****************************************************************/