using System.Text;
using System;

public class Hello
{
    static void Main()
    {
        var sb = new StringBuilder();
        var t = int.Parse(Console.ReadLine().Trim());
        while (t-- > 0)
        {
            var s = Console.ReadLine().Trim();
            sb.Append(getAns(s) + "\n");
        }
        Console.Write(sb);
    }
    static string getAns(string s)
    {
        var ok = "possible";
        var ng = "impossible";
        var sL = s.Length;
        var r = 0;
        var g = 0;
        var wgr = 0;
        for (int i = sL - 1; i >= 0; i--)
        {
            if (s[i] == 'R') r++;
            else if (s[i] == 'G')
            {
                if (r >= 1) { r--; g++; }
                else return ng;
            }
            else
            {
                if (g >= 1) { g--; wgr++; }
                else
                {
                    if (wgr >= 1) continue;
                    else return ng;
                }
            }
        }
        return (r == 0 && g == 0 && wgr >= 1 ? ok : ng);
    }
}