local q = io.read("*n", "*l")
for iq = 1, q do
  local s = io.read()
  local red, green = 0, 0
  local wcnt = 0
  local rcnt = 0
  local valid = true
  for i = #s, 1, -1 do
    local w = s:sub(i, i)
    if w == "R" then
      rcnt = rcnt + 1
      red = red + 1
    elseif w == "G" then
      if red == 0 then
        valid = false
        break
      else
        red = red - 1
        green = green + 1
      end
    else
      if green == 0 then
        if wcnt == 0 then
          valid = false
          break
        end
      else
        green = green - 1
        wcnt = wcnt + 1
      end
    end
  end
  if wcnt < rcnt then valid = false end
  print(valid and "possible" or "impossible")
end