#include <cstdio>
using ll = long long;
int main() {
    ll n; scanf("%lld", &n);
    ll g = n / 100000000 * 100000000;
    for (ll i = g+1; i <= n; ++ i) {
        g ^= i;
    }
    printf("%c\n", g ? 'O' : 'X');
    return 0;
}