#include <iostream>
#include <string>
#include <utility>
#include <algorithm>
#include <map>
#include <vector>
#include <cmath>
#include <cstdlib>
#include <queue>
#include <numeric>
#include <set>

using namespace std;

#define REP(i, n) for(int i = 0;i < n;i++)
#define REPR(i, n) for(int i = n;i >= 0;i--)
#define FOR(i, m, n) for(int i = m;i < n;i++)
#define FORR(i, m, n) for(int i = m;i >= n;i--)
#define REPO(i, n) for(int i = 1;i <= n;i++)
#define INF 999999999
#define MINF -999999999
#define ALL(n) n.begin(),n.end()
#define ll long long
#define MOD 1000000007

ll n;
int main() {
	cin >> n;
	n++;
	if (n == 2)cout << "O" << endl;
	else {
		REP(i, INF) {
			if (n % 2 != 0)break;
			n /= 2;
		}
		cout << (n == 1 ? "X" : "O") << endl;
	}

}