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 = new StringBuilder(sc.next()).reverse().toString().toCharArray();
            int r = 0;
            int g = 0;
            int w = 0;
            for (char c : arr) {
                if (c == 'R') {
                    r++;
                } else if (c == 'G') {
                    if (r == 0) {
                        r = -1;
                        break;
                    }
                    r--;
                    g++;
                } else {
                    w = Math.min(w + 1, g);
                }
            }
            if (r == 0 && g == w) {
                sb.append("possible");
            } else {
                sb.append("impossible");
            }
            sb.append("\n");
        }
        System.out.print(sb);
    }
}