import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int t = Integer.parseInt(br.readLine());
		PrintWriter pw = new PrintWriter(System.out);
		for (int i = 0; i < t; i++) {
			String[] sa = br.readLine().split(" ");
			String s = sa[1];
			if (s.indexOf("ooo") != -1
					|| s.indexOf("oo-") != -1
					|| s.indexOf("-oo") != -1
					|| s.indexOf("--o-") != -1
					|| s.indexOf("-o--") != -1
					|| s.indexOf("o-o") != -1
					) {
				pw.println("O");
			} else {
				pw.println("X");
			}
		}
		br.close();
		pw.flush();
	}
}