package main

import (
	"bufio"
	"bytes"
	"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++ {
		f := true
		b := []byte(nextLine())

		r, g := bytes.LastIndexByte(b, 'R'), bytes.LastIndexByte(b, 'G')
		if bytes.LastIndexByte(b, 'W') > g {
			ans = append(ans, imp...)
			continue
		}

		for len(b)-1 == r {
			b[r] = 'D'

			g := bytes.LastIndexByte(b, 'G')
			if g == -1 {
				f = true
				break
			}
			b[g] = 'D'

			w := bytes.LastIndexByte(b[:g+1], 'W')
			if w == -1 {
				f = true
				break
			}

			r = bytes.LastIndexByte(b[:r], 'R')
			f = false
			if r == -1 {
				break
			}
			b = b[:r+1]
		}
		if f {
			ans = append(ans, imp...)
			continue
		}

		if bytes.LastIndexByte(b, 'G') != -1 || bytes.LastIndexByte(b, 'R') != -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
}