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

using namespace std;

bool possible(const string& s) {
	int gCount = 0;
	for (size_t i = 0; i < s.size(); ++i) {
		char ch = s[i];
		if (ch == 'G') {
			++gCount;
		} else if (ch == 'R') {
			if (gCount == 0) {
				return false;
			}
			--gCount;
		}
	}
	if (gCount != 0) {
		return false;
	}
	int rootCount = 0;
	int whiteCount = 0;
	for (int i = s.size() - 1; i >= 0; --i) {
		char ch = s[i];
		if (ch == 'R') {
			++rootCount;
		} else if (ch == 'W') {
			if (rootCount == 0) {
				return false;
			}
			whiteCount = min(rootCount, whiteCount + 1);
		}
	}
	if (whiteCount != rootCount) {
		return false;
	}
	return true;
}

int main() {
	int t;
	cin >> t;
	for (int i = 0; i < t; ++i) {
		string s;
		cin >> s;
		cout << (possible(s) ? "possible" : "impossible") << endl;
	}
	return 0;
}