func main()
	var t: int :: cui@inputInt()
	for(1, t)
		var s: []char :: cui@input()
		var r: int :: 0
		var g: int :: 0
		var rg: bool :: false
		var ans: bool :: true
		; 逆順に見ていきます。
		for i(^s - 1, 0, -1)
			switch(s[i])
			case 'R'
				do r :+ 1
			case 'G'
				do rg :: true
				do g :+ 1
				if(r < g)
					do ans :: false
				end if
			case 'W'
				if(!rg & (r = 0 | g = 0))
					do ans :: false
				elif(r <> 0 & g <> 0)
					do r :- 1
					do g :- 1
				end if
			end switch
		end for
		if(r <> 0 | g <> 0)
			do ans :: false
		end if
		do cui@print((ans ?("possible", "impossible")) ~ "\n")
	end for
end func