#include <iostream>
using namespace std;

int main(){
    int a,b,c=0,d,e;
    cin>>a>>b;
    for (int i = a; i <= b; i++){
         e=i;
        for ( int j =1; j <=5; j++){
            d=e%10;
            if(d==2)c++;
            e=e/10;
            if(e==0)break;
        }
    }
    cout<<c;
return 0;
}