using System;
using System.Collections.Generic;
using System.Text;
using sc = Scanner;
using System.Collections;


class Program
{
    static void Main(string[] args)
    {
        Solve();
        Console.WriteLine("終了するにはなにかキーを押して下さい...");
        Console.ReadKey();
    }

    static void Solve()
    {
        int n = sc.NextInt();
        string[] quary = new string[n];
        for (int i = 0; i < n; i++)
        {
            quary[i] = Console.ReadLine();
        }
        for (int i = 0; i < n; i++)
        {
            string busData = quary[i];
            int checkNum = 0;
            bool completed = true;
            for (int j = 0; j < busData.Length; j++)
            {
                if (busData[j] == 'G')
                {
                    checkNum++;
                }
                if (busData[j] == 'R')
                {
                    checkNum--;
                    if (checkNum < 0)
                    {
                        Console.WriteLine("impossible");
                        completed = false;
                        break;
                    }
                }
            }
            if (completed)
            {
                if (checkNum == 0)
                {
                    Console.WriteLine("possible");
                }
                else
                    Console.WriteLine("impossible");
            }
        }
    }
}


public static class Scanner
{
    public static string[] NextStrArray()
    {
        return Console.ReadLine().Split(' ');
    }

    public static long[] NextLongArray()
    {
        string[] s = NextStrArray();
        long[] a = new long[s.Length];
        for (int i = 0; i < a.Length; i++)
        {
            a[i] = long.Parse(s[i]);
        }
        return a;
    }
    public static int[] NextIntArray()
    {

        string[] s = NextStrArray();
        int[] a = new int[s.Length];
        for (int i = 0; i < a.Length; i++)
        {
            a[i] = int.Parse(s[i]);
        }
        return a;
    }
    public static int NextInt()
    {
        string tmp = "";
        while (true)
        {
            string readData = char.ConvertFromUtf32(Console.Read());
            if (readData == " " || readData == "\n")
                break;
            tmp += readData;
        }
        return int.Parse(tmp);
    }
    public static double NextDouble()
    {
        string tmp = "";
        while (true)
        {
            string readData = char.ConvertFromUtf32(Console.Read());
            if (readData == " " || readData == "\n")
                break;
            tmp += readData;
        }
        return double.Parse(tmp);
    }
    public static long NextLong()
    {
        string tmp = "";
        while (true)
        {
            string readData = char.ConvertFromUtf32(Console.Read());
            if (readData == " " || readData == "\n")
                break;
            tmp += readData;
        }
        return long.Parse(tmp);
    }
    public static double[] NextDoubleArray()
    {

        string[] s = NextStrArray();
        double[] a = new double[s.Length];
        for (int i = 0; i < a.Length; i++)
        {
            a[i] = double.Parse(s[i]);
        }
        return a;
    }
}