# -*- coding:utf-8 -*-

def solve():
	s = raw_input()
	s = list(s)
	g = s.count("G")
	r = s.count("R")
	if g != r:
		print "impossible"
		return
	i = 1
	gg = s[::-1].index("G")
	ww = s[::-1].index("W")
	if ww < gg:
		print "impossible"
		return
	while i <= g:
		gg = s[::-1].index("G")
		rr = s[::-1].index("R")
		if gg < rr:
			print "impossible"
			return
		s[len(s)-gg -1] = s[len(s) - rr -1] = "W"
		i += 1
	print "possible"




if __name__ == "__main__":
	n = input()
	for i in xrange(n):
		S = raw_input()
		need = False
		w = r = cnt = 0
		for s in S:
			if s == "G":
				r += 1
				w -= 1
				need = False
			elif s == "R":
				r -= 1
			else:
				w += 1
				need = True
			if r < 0 or w < 0:
				print "impossible"
				break
		else:
			if r == 0 and not need:
				print "possible"
			else:
				print "impossible"