#include <iostream>
using namespace std;

int main(){
    int a, b;
    cin >> a >> b;
    
    if(a < 23 && (b >= 23 && b <= 25)){
        b -= 22;
        cout << b;
    }else if(b > 25 && (a >= 23 && a <= 25)){
        a = 26 - a;
        cout << a;
    }else if((a >= 23 && a <= 25) && (b >= 23 && b <= 25)){
        b -= a + 1;
        cout << b;
    }else{
        cout << 0;
    }
    
    return 0;
}