#yuki_154

n=int(raw_input())
for i in xrange(n):
 s=raw_input()[::-1]
 red=green=0
 pas=True
 res=False
 for c in s:
  if c=='R':
   red+=1
  if c=='G':
   if red<=0:
    pas=False
    break
   red-=1
   green+=1
  if c=='W':
   if green<=0 and res==False:
    pas=False
    break
   if green<1:
    green=0
   else:
    green-=1
   res=True
 if pas==True and red==0 and green==0:
  print "possible"
 else:
  print "impossible"