#include <stdio.h>

int main(void)
{
	int times, i, j, white, green, red;
	char bus[1001];

	scanf("%d", &times);

	for (i = 0;i < times;i++) {
		scanf("%s", bus);

		j = white = green = red = 0;
		while (bus[j] != '\0') {
			if (bus[j] == 'W')white++;
			if (bus[j] == 'G')green++;
			if (bus[j] == 'R')red++;
			if ((white < green) || (green < red)) {
				goto IMPOSSIBLE;
			}
			j++;
		}

		if (green == 0 || red == 0 || bus[j-1]=='W' || green != red) {
			goto IMPOSSIBLE;
		}

		printf("possible\n");
		continue;
	IMPOSSIBLE:
		printf("impossible\n");
		continue;
	}
	return 0;
}