#include "bits/stdc++.h"
using namespace std;

bool check(string S){
	vector<int> count(3);
	bool flag = true;
	int pp = 0;
	for (int i = S.size() - 1; i >= 0; i--)
	{
		int r = 0;
		if (S[i] == 'G') r = 1;
		if (S[i] == 'R') r = 2;
		count[r]++;
		if (count[0] != 0 && count[1] == 0) return false;
		if (count[0] != 0 && count[2] == 0) return false;
		if (count[2] < count[1]) return false;
		if (r == 0) pp = min(pp + 1, count[1]);
	}
	if (count[2] != count[1]) return false;
	if (count[0] < count[1]) return false;
	if (pp != count[1]) return false;
	return true;
}

int main() {
	int N;
	cin >> N;
	for (int t = 0; t < N; t++)
	{
		string S;
		cin >> S;
		if (check(S)) cout << "possible" << endl;
		else cout << "impossible" << endl;
	}
}