import java.util.Arrays;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Scanner;
import java.util.Set;

public class Main {
	
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		
		final int T = sc.nextInt();
		for(int tt = 0; tt < T; tt++){
			final char[] input = sc.next().toCharArray();
			
			LinkedList<Integer> R_queue = new LinkedList<Integer>();
			LinkedList<Integer> G_queue = new LinkedList<Integer>();
			
			boolean ok = true;
			for(int i = input.length - 1; i >= 0; i--){
				if(input[i] == 'R'){
					R_queue.add(i);
				}else if(input[i] == 'G'){
					G_queue.add(i);
				}else if(input[i] == 'W'){
					if(R_queue.isEmpty() || G_queue.isEmpty()){
						ok = false;
						break;
					}
				}
				
				while(R_queue.size() >= 2 && G_queue.size() >= 2){
					R_queue.remove();
					G_queue.remove();
					
					while(!G_queue.isEmpty() && G_queue.peek() > R_queue.peek()){
						G_queue.remove();
					}
				}
				
				if(R_queue.size() < G_queue.size()){
					ok = false;
					break;
				}
				
				//System.out.println(i + " " + R_queue + " " + G_queue);
			}
			
			System.out.println(ok ? "possible" : "impossible");
			
		}
		
	}
	
}