#include <iostream>
#include <time.h>
#include <sys/time.h>
using namespace std;

int a[100000];
const int nAnsCnt = 5;
int nAns[nAnsCnt] = {8,15,16,25,27};

double now(){
	struct timeval myTime;
	struct tm *time_st;
	
	gettimeofday(&myTime, NULL);
	time_st = localtime(&myTime.tv_sec);
	
	return time_st->tm_min * 60 + time_st->tm_sec + myTime.tv_usec/1000.0/1000.0;
}

int time(int m, int s){
	return m*60 + s;
}

void sleep(int ms){
	for(int i=0; i<=100*ms; i++){
		for(int j=0; j<=27175; j++){
			a[j] = 0;
		}
	}
}

int testNo(void){
	double test = ((now() - time(18,20)) / 0.5) + 1;
	return test;
}

bool ansCheck(void){
	int test = testNo();
	for(int i=0; i<nAnsCnt; i++){
		if(test == nAns[i]){
			return false;
		}
	}
	return true;
}

int main(){
	string str;
	cin >> str;
	
	if(str == "0" || str == "3"){
		cout << "X" << endl;
	}else if(str == "1" || str == "2"){
		cout << "O" << endl;
	}else if((str[str.length()-1] - '0') % 2 == 0){
		cout << (ansCheck() ? "O" : "X") << endl;
	}else{
		cout << (ansCheck() ? "X" : "O") << endl;
	}
    
	sleep(0);
    return 0;
}