include

using namespace std;

int main() {

int i, a, b, c = 0, m, n;
scanf("%d%d", &n, &m);
for (int i = n; i <= m; i++) {
	int a = i;
	while (a > 0) {
		int b = a % 10;
		if (b == 2) {
			c++;
		}
		a = a / 10;
	}
}

printf("%d", c);

return 0;

}