#include<iostream>
#include<string>

void solve() {
	std::string s;

	std::cin >> s;

	int green = 0, white = 0;
	for (int i = 0; i < s.length(); i++) {
		if (s[i] == 'W') white++;
		if (s[i] == 'G') green++;
		if (s[i] == 'R') {
			if (green == 0 || white == 0) {
				std::cout << "impossible" << std::endl;
				return ;
			}
			white--;
			green--;
		}
	}

	if (green != 0 || s.back() != 'R') {
		std::cout << "impossible" << std::endl;
	} else {
		std::cout << "possible" << std::endl;
	}
}

int main() {
	int n;

	std::cin >> n;

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

	return 0;
}