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

int main() {
	int A, B, ans = 0;
	bool X[32] = {};
	X[23] = X[24] = X[25] = true;
	cin >> A >> B;
	for (int i = A; i <= B; i++) X[i] = false;
	for (int i = 23; i <= 25; i++) ans += X[i];
	cout << ans << endl;
}