//丹阳新区实小路彦
#include <bits/stdc++.h>
using namespace std;

int main()
{
    int l, r;
    cin >> l >> r;
    int res = 0; 
    for (int i = l; i <= r; i ++ )
        for (int j = i; j; j /= 10)
            if (j % 10 == 2) res++;
    cout << res << endl;
    return 0;
}