#include <bits/stdc++.h>
using namespace std;
int main(){
    int a, b;
    cin >> a >> b;
    if(a > 25 || b < 23){
        cout << 3 << endl;
        return 0;
    }
    if(a < 23){
        if(b < 23 || b > 25){
            cout << 3 << endl;
            return 0;
        }
        cout << b - 23 << endl;
        return 0;
    }
    if(b > 25){
        if(a < 23 || a > 25)    cout << 3 << endl;
        else    cout << 25 - a << endl;
    }
    else{
        if(a < 23)  cout << b - 23 << endl;
        else    cout << b - a - 1 << endl;
    }
}