#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() {
	long long n;
	cin >> n;

	bool zero = true;
	for (int i = 0; i < 32; i++) {
		long long cnt = n / (1LL << i + 1) * (1LL << i) + max(0LL, n % (1LL << i + 1) - (1LL << i) + 1);
		if (cnt % 2 != 0) {
			zero = false;
		}
	}

	cout << (zero ? "X" : "O") << endl;
}