#include <stdio.h>

int main() {
	int t, w, g, r, p[1000], i;
	char s;

	scanf("%d", &t);
	getchar();
	for (i = 0; i < t; i++) {
		p[i] = w = g = r = 0;
		while ((s = getchar()) != '\n') {
			if (p[i] != -1) {
				if (s == 'W') w++;
				else if (s == 'G') g++;
				else if (s == 'R') r++;
				if (r > g || g > w) p[i] = -1;
			}
		}
		if (r != g) p[i] = -1;
	}

	for (i = 0; i < t; i++) {
		if (p[i] == -1) printf("impossible\n");
		else printf("possible\n");
	}

	return 0;
}