for _ in[0]*input():
	s=list(raw_input())
	while"W"in s:
		w=s.index("W")
		if "G"not in s:
			break
		g=s.index("G")
		if "R"not in s:
			break
		r=s.index("R")
		if w<g<r:
			s.pop(r)
			s.pop(g)
			s.pop(w)
		else:
			break
	if s.count("W")==len(s):
		print"possible"
	else:
		print"impossible"