#!/usr/bin/ruby
puts$<.drop(1).map{|e|
	s=e.chomp
	if s.include?('W')
		next :impossible if (s.rindex('W')||99999)>=(s.rindex('G')||99999) || (s.rindex('G')||99999)>(s.rindex('R')||99999)
	end
	g=0
	s=s.tr('W','')
	s.chars{|c|
		if c=='R'
			g-=1
			g=0 if g<0
		else
			g+=1
		end
	}
	g>0 ? :impossible : :possible
}