#include <iostream>
#include <string>
#include <vector>

using namespace std;

bool judge(string);

int main(int argc, char *argv[]) {
	int T;
	string pattern;
	cin >> T;
	for (int i = 0; i < T; i++) {
		cin >> pattern;
		cout << (judge(pattern) ? "possible" : "impossible") << endl;
	}
	return 0;
}
bool judge(string s) {
	vector<int> count(3);
	vector<int> final(3);
	int len = s.length();
	int ch;
	int r;
	for (int i = 0; i < len; i++) {
		ch = s[i];
		switch (ch) {
		case 'W':
			r = 0;
			break;
		case 'G':
			r = 1;

			break;
		case 'R':
			r = 2;

			break;
		}
		if (count[1] > count[0])
			return false;
		if (count[2] > count[1])
			return false;
		count[r]++;
		final[r] = i;
	}
	if (count[2] == 0)
		return false;
	if (count[2] != count[1])
		return false;
	if ((final[0] > final[1]) || (final[0] > final[2]))
		return false;
	return true;
}