#include <stdio.h>
#include <string.h>

int main(void)
{
	char S[1001];
	int T, G, R, length, tmp, i, j;
	scanf("%d", &T);
	for (i = 0; i < T; ++i) {
		scanf("%s", S);
		G = 0;
		R = 0;
		length = strlen(S);
		for (j = 0; j < length; ++j) {
			if (S[j] == 'G') ++G;
			else if (S[j] == 'R') ++R;
		}
		if (G == R) {
			tmp = 0;
			for (j = 0; j < length; ++j) {
				if (S[j] == 'G') ++tmp;
				else if (S[j] == 'R') --tmp;
				if (tmp < 0) break;
			}
			if (j != length) puts("impossible");
			else puts("possible");
		}
		else puts("impossible");
	}
	return 0;
}