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


int main() {
	int N;
	cin >> N;
	for (int t = 0; t < N; t++)
	{
		string S;
		cin >> S;

		vector<int> count(3);
		bool flag = true;
		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) flag = false;
			if (count[0] != 0 && count[2] == 0) flag = false;
			if (count[2] < count[1]) flag = false;
		}
		if (count[2] != count[1]) flag = false;
		if (count[0] < count[1]) flag = false;

		if (flag) cout << "possible" << endl;
		else cout << "impossible" << endl;
	}
}