package main

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

var sc = bufio.NewScanner(os.Stdin)

func main() {
	sc.Split(bufio.ScanWords)
	t := nextInt()
	r := regexp.MustCompile(`G.*?R`)

	for i := 0; i < t; i++ {
		b := []byte(strings.Replace(nextLine(), "W", "", -1))
		for j := 0; j < 3; j++ {
			loc := r.FindIndex(b)
			if loc == nil {
				break
			}

			b[loc[0]], b[loc[1]-1] = 'W', 'W'
			b = []byte(strings.Replace(string(b), "W", "", -1))
		}
		if len(b) == 0 {
			fmt.Println("possible")
			continue
		}
		fmt.Println("impossible")
	}
}

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

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