using System;
using System.Collections.Generic;
using System.Text;
using System.Linq;

class Program
{
    public void Proc()
    {
        Reader.IsDebug = false;
        int queryCount = int.Parse(Reader.ReadLine());
        for(int i=0; i<queryCount; i++) {
            if(this.GetAns(Reader.ReadLine())) {
                Console.WriteLine("possible");
            } else {
                Console.WriteLine("impossible");
            }
        }

    }

    private bool GetAns(String inpt) {

        Dictionary<int, char> rosen = new Dictionary<int, char>();
        char[] rev = inpt.Reverse().ToArray();
        for(int i=0; i<rev.Length; i++) {
            if(rev[i] == 'R') {
                rosen.Add(rosen.Count, rev[i]);
            } else if(rev[i] == 'G') {
                if(rosen.Count(a=>a.Value == 'R') == 0) {
                    return false;
                }
                int idx = rosen.First(a=>a.Value == 'R').Key;
                rosen[idx] = 'G';
            } else {
                if(rosen.Count(a=>a.Value == 'G') == 0) {
                    if(rosen.Count(a=>a.Value == 'W') == 0) {
                        return false;
                    }
                } else {
                    int idx = rosen.First(a=>a.Value == 'G').Key;
                    rosen[idx] = 'W';
                }
            }
        }
        return !(rosen.Count(a=>a.Value != 'W') > 0);
    }


    public class Reader
    {
        public static bool IsDebug = true;
        private static String PlainInput = @"


5
WWWWWWWWWGR
WWWWGWGRR
WWWWWWWWWWWWWWGRRG
WGRWGR
WWWWWWWWWWWWWWWWWGGWGWGGWGWGGGWGG


 
";
        private static System.IO.StringReader Sr = null;
        public static string ReadLine()
        {
            if (IsDebug)
            {
                if (Sr == null)
                {
                    Sr = new System.IO.StringReader(PlainInput.Trim());
                }
                return Sr.ReadLine();
            }
            else
            {
                return Console.ReadLine();
            }
        }

    }
    static void Main()
    {
        Program prg = new Program();
        prg.Proc();
    }
}