def check(S):
	depth = 0
	for c in S:
		if c == 'G':
			depth += 1
		elif c == 'R':
			depth -= 1
		if depth < 0:
			return False
	return depth == 0

T = input()
for i in xrange(T):
	S = raw_input()
	if check(S):
		print 'possible'
	else:
		print 'impossible'