package main

import (
	"fmt"
	"strings"
)

func solve() (res string) {
	res = "impossible"
	var S string
	fmt.Scan(&S)
	sr := strings.NewReader(S)
	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() {
	var N int
	fmt.Scan(&N)
	for i := 0; i < N; i++ {
		fmt.Println(solve())
	}
}