package main

import (
	"fmt"
)

func solve() (res string) {
	res = "impossible"
	var S string
	fmt.Scan(&S)
	var W, G, R int
	for _, r := range S {
		switch r {
		case 'W':
			W++
		case 'G':
			if W == 0 {
				return
			}
			W = 0
			G++
		case 'R':
			R++
		}
		if R > G {
			return
		}
	}
	if W == 0 && G == R {
		res = "possible"
	}
	return
}

func main() {
	var N int
	fmt.Scan(&N)
	for i := 0; i < N; i++ {
		fmt.Println(solve())
	}
}