#include<iostream>
#include<string>
#include<algorithm>

void solve() {
	std::string s;

	std::cin >> s;

	int end_green = s.rfind('G'),
		end_red = s.rfind('R'),
		white_no = std::count(s.begin(), s.end(), 'W'),
		green_no = std::count(s.begin(), s.end(), 'G'),
		red_no = std::count(s.begin(), s.end(), 'R');

	if (white_no < green_no || green_no != red_no || end_red < end_green ||
		white_no == 0 || green_no == 0 || red_no == 0) {
		std::cout << "impossible" << std::endl;
		return;
	}
	for (int i = end_green; i < s.length(); i++) {
		if (s[i] == 'W') {
			std::cout << "impossible" << std::endl;
			return;
		}
	}

	std::cout << "possible" << std::endl;
}

int main() {
	int n;
	std::cin >> n;

	for (int i = 0; i < n; i++) {
		solve();
	}

	return 0;
}