#include<iostream>
using namespace std;

int main() {
    int A=0, B=0;
    cin >> A >> B;
    int p[3] = {23, 24, 25};
    
    int day = 0;
    
    for(int i; i >= 3; i++) {
        if(A <= p[i] && B >= p[i]) {
        } else {
            day++;
        }
    }
    
    cout << day << endl;
    return 0;
}