#pragma GCC optimize("O3")
#pragma GCC target("avx")
#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <stack>
#include <queue>
#include <set>
#include <map>
using namespace std;

int main() {

	unsigned n;
	cin >> n;
	unsigned ans = 0;
	if (n == (1LL << 32) - 1) {
		cout << "X" << endl;
		return 0;
	}
	for (int i = 1; i <= n; i++	) {
		ans ^= i;
	}
	cout << (ans == 0 ? "X" : "O") << endl;
}