using System;
using System.IO;
using System.Linq;
using System.Text;
using System.Diagnostics;
using System.Collections.Generic;
using System.Text.RegularExpressions;
using Enu = System.Linq.Enumerable;

class Program
{
    void Solve()
    {
        //reader = new Reader(new StreamReader(@"D:\in.txt"));
        int T = reader.Int();
        for (int ti = 0; ti < T; ti++)
        {
            var A = reader.String().Select(c => "WGR".IndexOf(c)).ToArray();
            var pos = Enu.Range(0, 3).Select(i => new List<int>()).ToArray();
            for (int i = 0; i < A.Length; i++)
                pos[A[i]].Add(i);
            if (Valid(pos)) Console.WriteLine("possible");
            else Console.WriteLine("impossible");
        }
        Console.ReadLine();
    }

    private bool Valid(List<int>[] pos)
    {
        if (pos[1].Count == 0) return false;
        if (pos[1].Count != pos[2].Count) return false;
        if (pos[0].Count < pos[1].Count) return false;
        for (int i = 0; i < 3; i++) pos[i].Reverse();
        int wi = -1;
        for (int i = 0; i < pos[1].Count; i++)
        {
            if (pos[1][i] > pos[2][i]) return false;
            wi++;
            while (wi < pos[0].Count && pos[0][wi] > pos[1][i])
            {
                if (i == 0) return false;
                wi++;
            }
            if (wi == pos[0].Count) return false;
        }
        return true;
    }

    



    Reader reader = new Reader(Console.In);
    static void Main() { new Program().Solve(); }
}

class Reader
{
    private readonly TextReader reader;
    private readonly char[] separator = { ' ' };
    private readonly StringSplitOptions removeOp = StringSplitOptions.RemoveEmptyEntries;
    private string[] A = new string[0];
    private int i;

    public Reader(TextReader r) { reader = r; }
    public bool HasNext() { return Enqueue(); }
    public string String() { return Dequeue(); }
    public int Int() { return int.Parse(Dequeue()); }
    public long Long() { return long.Parse(Dequeue()); }
    public double Double() { return double.Parse(Dequeue()); }
    public int[] IntLine() { var s = Line(); return s == "" ? new int[0] : Array.ConvertAll(Split(s), int.Parse); }
    public int[] IntArray(int N) { return Enu.Range(0, N).Select(i => Int()).ToArray(); }
    public int[][] IntGrid(int H) { return Enu.Range(0, H).Select(i => IntLine()).ToArray(); }
    public string[] StringLine(int N) { return Enu.Range(0, N).Select(i => Line()).ToArray(); }
    public string Line() { return reader.ReadLine().Trim(); }
    private string[] Split(string s) { return s.Split(separator, removeOp); }
    private bool Enqueue()
    {
        if (i < A.Length) return true;
        string line = reader.ReadLine();
        if (line == null) return false;
        if (line == "") return Enqueue();
        A = Split(line);
        i = 0;
        return true;
    }
    private string Dequeue() { Enqueue(); return A[i++]; }
}