using System;
using System.Linq;

namespace No154_1{
    public class Program{
        public static void Main(string[] args){
            Console.ReadLine();
            string str;
            while((str = Console.ReadLine()) != null){
                int cntW = 0, cntG = 0, cntR = 0;
                var possible = true;

                foreach(var c in str){
                    if(c == 'W') cntW++;
                    if(c == 'G') cntG++;
                    if(c == 'R') cntR++;
                    if(cntW < cntG || cntG < cntR) possible = false;
                }

                if(cntG != cntR || str.Skip(str.LastIndexOf('G') + 1).Any(c => c == 'W'))
                    possible = false;

                Console.WriteLine((possible ? "" : "im") + "possible");
            }
        }
    }
}