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


signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(20);
    
    ll n;
    cin>>n;
    ll sum = n*(n+1)/2;
    if(sum%2==0 && n%2){
        cout << "X\n";
    }
    else if(sum%2==0){
        cout << "O\n";
    }
    else if(n%2){
        cout << "O\n";
    }
    else cout << "X\n";
}