for _ in[0]*input():
	s=raw_input()
	w=g=r=0
	for c in s[::-1]:
		if c=="R":
			r+=1
		elif c=="G":
			g+=1
			if g>r:
				print"impossible"
				break
		elif c=="W":
			w+=1
			if g>0 and r>0:
				g-=1
				r-=1
				w-=1
	if g==0 and r==0:
		print"possible"
	else:
		print"impossible"