#include <stdio.h>

int main(void) {
	int i, j, t;
	int g, r;
	int flag;
	char s[1001];
	scanf("%d", &t);
	for(i = 0;i < t;i++){
		scanf("%s", s);
		g = 0;
		r = 0;
		j = 0;
		flag = 0;
		while(s[j] != '\0'){
			if(s[j] == 'G'){
				g++;
				flag = 0;
			}
			if(s[j] == 'R'){
				r++;
				flag = 0;
			}
			if(s[j] == 'W'){
				flag = 1;
			}
			if(r > g){
				break;
			}
			j++;
		}
		if(flag == 1 || g != r){
			printf("impossible\n");
		}
		else{
			printf("possible\n");
		}
		
	}

	return 0;
}