using System;

class Bus
{
	static public void Main(String[] args)
	{
		int T = int.Parse(Console.ReadLine());

		for(int i=0; i < T; i++)
		{
			string S = Console.ReadLine();
			int count = 0;

			foreach(char s in S)
			{
				if(s == 'G')
				{
					count++;
				}
				else if(s == 'R')
				{
					if(--count < 0)
					{
						Console.WriteLine("impossible");
						break;
					}
				}
			}

			if(count == 0)
			{
				Console.WriteLine("possible");
			}
			else if(count > 0)
			{
				Console.WriteLine("impossible");
			}

		}
	}
}