#include <iostream>
using namespace std;
int main(){
int L,R,sum=0,a;
cin >> L >> R ;
for(int i=L;i<=R;i++){
a = i;
while(a>0){
if (a % 10 == 2)
sum = sum + 1;
a = a / 10;
}
}
cout << sum << endl;
return 0;
}