puts $<.drop(1).map{|s|
  a=s.reverse.chars.inject([0,0,0]){|(r,g,w),c|
    case c
    when ?R
      r+=1
    when ?G
      break if r==0
      r-=1
      g+=1
    when ?W
      if g>0
        g-=1
        w+=1
      elsif w>0
        w+=1
      else
        break
      end
    end
    [r,g,w]
  }
  (a&&a[0]==0&&a[1]==0)?"possible":"impossible"
}