n = int(input())

for i in range(n):

	syscnt = 0
	stk = []

	s = raw_input()

	possible = True
	chkind = 0
	wcount = 0
	for j in range(len(s)):
		
		if s[j] == 'W':
			wcount += 1

		if s[j] == 'G':
			stk.append('g')
			syscnt += 1
			if wcount < syscnt:
				possible = False 
			chkind = j
			
		elif s[j] == 'R':
			if not stk :
				possible = False
			else :
				stk.pop()
			
	if stk :
		possible = False

	for i in range(chkind,len(s)):
		if s[i] == 'W':
			possible = False

	print 'possible' if possible else 'impossible'