# coding: utf-8
#yuki_154

t=int(raw_input())
for i in xrange(t):
 s=raw_input()
 rgcount=0
 rflag=False
 gflag=False
 if len(s)==1:
  print "impossible"
  continue
 if s=="GR":
  print "impossible"
  continue
 for j in xrange(len(s)):
  st=s[-1]
  if st=='R':
   rgcount+=1
   rflag=True
  elif st=='G':
   rgcount-=1
   gflag=True
  elif st=='W':
   if rflag==False or gflag==False:
    print "impossible"
    break
  if rgcount<0:
   print "impossible"
   break
  s=s[:-1]
  if len(s)==0:
   print "possible"