for _ in[0]*input():
	s=list(raw_input())
	while 1:
		w=g=r=-1
		for i in xrange(len(s)):
			if s[i]=="W" and w==-1:
				w=i
			elif s[i]=="G" and g==-1:
				g=i
			elif s[i]=="R" and r==-1:
				r=i
			if w>=0 and g>=0 and r>=0:
				break
		if w>=0 and g>=0 and r>=0 and w<g<r:
			s[w]=s[g]=s[r]=None
		elif g==-1 and r==-1:
			print"possible"
			break
		else:
			print"impossible"
			break