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

int a ,b;

int main()
{
    cin>>a;
    for(int b = 0; b < 2025;b++)
    {
        //int c = (a & b) +(a | b);
        if((a & b) +(a | b) == 2025)
        {
            cout<<b<<endl;
            return 0;
        }
    }
    cout<<-1<<endl;
}