package main

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

var sc = bufio.NewScanner(os.Stdin)

func next() string {
	sc.Split(bufio.ScanWords)
	if !sc.Scan() {
		panic("could not scan a word from the reader")
	}
	return sc.Text()
}

func nextInt() int {
	i, e := strconv.Atoi(next())
	if e != nil {
		panic(e)
	}
	return i
}

func nextLong() int64 {
	i, e := strconv.ParseInt(next(), 10, 64)
	if e != nil {
		panic(e)
	}
	return i
}

func nextLine() string {
	sc.Split(bufio.ScanLines)
	if !sc.Scan() {
		panic("could not scan a line from the reader")
	}
	return sc.Text()
}

func solve() (res string) {
	res = "impossible"
	sr := strings.NewReader(next())
	var W0, W1, G, R int
	for {
		b, e := sr.ReadByte()
		if e != nil {
			break
		}
		switch b {
		case byte('W'):
			W0++
			W1++
		case byte('G'):
			W0 = 0
			G++
		case byte('R'):
			R++
		}
		if R > G || G > W1 {
			return
		}
	}
	if W0 == 0 && G == R {
		res = "possible"
	}
	return
}

func main() {
	N := nextInt()
	for i := 0; i < N; i++ {
		fmt.Println(solve())
	}
}