#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <utility>
#include <string>

using namespace std;

int main() {
	int t, w, g, r;
	string s;

	cin >> t;
	vector<bool> ans(t, false);
	for (int i = 0; i < t; i++) {
		cin >> s;
		int n = s.size();
		bool isPossible;

		w = g = r = 0;
		for (int i = 0; i < n; i++) {
			isPossible = true;
			if (s[i] == 'W') {
				w++;
			} else if (s[i] == 'G') {
				g++;
				if (w < g) {
					isPossible = false;
					break;
				}
			} else if (s[i] == 'R') {
				r++;
				if (g < r || w < r) {
					isPossible = false;
					break;
				}
			}
		}
		if (r == 0 || r != g || s[n - 1] != 'R') {
			isPossible = false;
		}
		if (isPossible) {
			for (int i = n - 1; i >= 0; i--) {
				if (s[i] == 'G') {
					break;
				}
				if (s[i] == 'W') {
					isPossible = false;
					break;
				}
			}
		}

		ans[i] = isPossible;
	}

	for (int i = 0; i < t; i++) {
		cout << (ans[i] ? "possible" : "impossible") << endl;
	}
	return 0;
}