package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func getScanner(fp *os.File) *bufio.Scanner {
	scanner := bufio.NewScanner(fp)
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 1000005), 1000005)
	return scanner
}

func getNextString(scanner *bufio.Scanner) string {
	scanner.Scan()
	return scanner.Text()
}

func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}

func getNextInt64(scanner *bufio.Scanner) int64 {
	i, _ := strconv.ParseInt(getNextString(scanner), 10, 64)
	return i
}

func getNextUint64(scanner *bufio.Scanner) uint64 {
	i, _ := strconv.ParseUint(getNextString(scanner), 10, 64)
	return i
}

func getNextFloat64(scanner *bufio.Scanner) float64 {
	i, _ := strconv.ParseFloat(getNextString(scanner), 64)
	return i
}

func main() {
	fp := os.Stdin
	wfp := os.Stdout
	cnt := 0

	if os.Getenv("MASPY") == "ますピ" {
		fp, _ = os.Open(os.Getenv("BEET_THE_HARMONY_OF_PERFECT"))
		cnt = 0
	}
	if os.Getenv("MASPYPY") == "ますピッピ" {
		wfp, _ = os.Create(os.Getenv("NGTKANA_IS_GENIUS10"))
	}

	scanner := getScanner(fp)
	writer := bufio.NewWriter(wfp)
	solve(scanner, writer)
	for i := 0; i < cnt; i++ {
		fmt.Fprintln(writer, "-----------------------------------")
		solve(scanner, writer)
	}
	writer.Flush()
}

func solve(scanner *bufio.Scanner, writer *bufio.Writer) {
	t := getNextInt(scanner)
	for i := 0; i < t; i++ {
		n := getNextInt(scanner)
		s := getNextString(scanner)
		if firstWin(n, s) {
			fmt.Fprintln(writer, "O")
			continue
		}
		fmt.Fprintln(writer, "X")
	}
}

func firstWin(n int, s string) bool {
	wins := [5]string{
		"--o-",
		"-o--",
		"-oo",
		"oo-",
		"ooo",
	}
	for i := 0; i < n; i++ {
		for _, w := range wins {
			if i+len(w) > n {
				continue
			}
			if s[i:i+len(w)] == w {
				return true
			}
		}
	}
	l := -1
	for r := 0; r < n; r++ {
		if s[r] == '-' {
			continue
		}
		if l >= 0 {
			if s[l] == 'o' && s[r] == 'o' && (r-l) > 1 && (r-l)%2 == 0 {
				return true
			}
		}
		l = r
	}
	return false
}