include

using namespace std;

int main() {

int l, r, c, d, e = 0 ;
cin >> l >> r;
while (l <= r) {
	for (c = l; c > 0; c = c / 10) {
		if (c % 10 == 2) {
			e++;
		}
	}
	l++;
}
cout << e;
return 0;

}