import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < n; i++) {
            char[] arr = sc.next().toCharArray();
            int count = 0;
            int wcount = 0;
            for (char c : arr) {
                if (c == 'G') {
                    count++;
                    wcount = 0;
                } else if(c == 'R') {
                    count--;
                } else {
                    wcount++;
                }
                if (count < 0) {
                    break;
                }
            }
            if (count == 0 && wcount == 0) {
                sb.append("possible");
           } else {
                sb.append("impossible");
             }
            sb.append("\n");
        }
        System.out.print(sb);
    }
}