/**************************************************************** 
 * Description: 
 * Author: Alex Li
 * Date: 2024-06-10 17:00:28
 * LastEditTime: 2024-06-10 17:03:53
****************************************************************/
#include <iostream>
using namespace std;
int sum;
void bit(int n){
    int m;
   for(int i=0; i<6;i++){
          m=n%10;
          if(m==2)sum++;
          n=n/10;
          if(n==0)break;
   }
}

int main(){
    int L,R;
    cin>>L>>R;
    for(int i=L;i<=R;i++){
        bit(i);
    }
    cout<<sum;
}