# coding: utf-8
#yuki_154

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