import java.util.*;

public class Main {
    private static Scanner sc = new Scanner(System.in);
    public static void main(String[] args) throws Exception {
        int n = sc.nextInt();
        for (int i = 0;i < n;i++) {
            if (solve(sc.next())) {
                System.out.println("possible");
            } else {
                System.out.println("impossible");
            }
        }
    }
    
    private static boolean solve(String s) {
        int w = 0;
        List<Integer> g = new ArrayList<>();
        List<Integer> r = new ArrayList<>();
        
        for (int i = s.length()-1;i >= 0;i--) {
            char c = s.charAt(i);
            if (c == 'W') {
                if (g.isEmpty() || r.isEmpty()) {
                    return false;
                } else {
                    w++;
                }
            }
            if (c == 'G') g.add(i);
            if (c == 'R') r.add(i);
        }

        if (g.size() != r.size()) return false;
        if (w < g.size()) return false;
        
        for (int i = 0;i < g.size();i++) {
            if (r.get(i) < g.get(i)) {
                return false;
            }
        }
        
        return true;
    }
}