#include <bits/stdc++.h>  
using namespace std;  

int main(){
	unsigned left, right;
    cin >> left >> right;
    unsigned count = 0;
    for (unsigned i = left; i <= right; ++i)
    {
        if (i / 10000 == 2)
        {
            count++;
        }
        if ((i / 1000) % 10 == 2)
        {
            count++;
        }
        if ((i / 100) % 10 == 2)
        {
            count++;
        }
        if ((i / 10) % 10 == 2)
        {
            count++;
        }
        if (i % 10 == 2)
        {
            count++;
        }
    }
    cout << count << endl;
	return 0;
}