package main

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

var sc = bufio.NewScanner(os.Stdin)

func main() {
	sc.Split(bufio.ScanWords)
	t := nextInt()
	ans := make([]byte, 0, 10000)
	imp, po := []byte("impossible\n"), []byte("possible\n")

	for i := 0; i < t; i++ {
		s := nextLine()
		flag := true
		count := make([]int, 3)
		min := 0
		for i := len(s) - 1; i >= 0; i-- {
			switch c := s[i]; c {
			case 'W':
				count[0]++
				if min != 0 {
					min--
				}
			case 'G':
				count[1]++
				min++
			case 'R':
				count[2]++
			}
			if count[2] == 0 && count[0] == 1 {
				flag = false
				break
			}

			if count[2] == 0 && count[1] == 1 {
				flag = false
				break
			}

			if count[1] == 0 && count[0] == 1 {
				flag = false
				break
			}

			if count[1] > count[2] {
				flag = false
				break
			}

		}

		if !flag {
			ans = append(ans, imp...)
			continue
		}

		if min != 0 {
			ans = append(ans, imp...)
			continue
		}

		if count[2] != count[1] {
			ans = append(ans, imp...)
			continue
		}

		ans = append(ans, po...)
	}
	fmt.Println(string(ans))
}

func nextLine() string {
	sc.Scan()
	return sc.Text()
}

func nextInt() int {
	i, _ := strconv.Atoi(nextLine())
	return i
}