import java.io.*;
public class Main{
public static void main(String[] agrs) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
String[] s = br.readLine().split(" ");
int n1 = Integer.parseInt(s[0]);
int n2 = Integer.parseInt(s[1]);
String s1 = "";
for (int i=n1;i<=n2;i++){
s1 = s1.concat(Integer.toString(i));//将所有的连续的数字组成字符串
}
char[] c = s1.toCharArray();字符串转换字符数组
char search = '2';
int count = 0;
for(char item:c){//字符数组中查找需要找到元素的个数
if (item == search){
count++;
}
}
System.out.println(count);
}
}