T = gets.to_i
S = T.times.map {gets.chomp}

def f(s)
  r = 0
  g = 0
  w = 0
  s.reverse.each_char do |c|
    if c == "R"
      r += 1
    elsif c == "G"
      if r == 0
        return "impossible"
      else
        r -= 1
        g += 1
      end
    elsif c == "W"
      if g == 0 and w == 0
        return "impossible"
      else
        g = [g - 1, 0].max
        w += 1
      end
    end
  end
  if r == 0 and g == 0
    "possible"
  else
    "impossible"
  end
end

ans = S.map {|s| f(s)}
puts ans