#include <iostream>
#include <string>
#include <algorithm>
using namespace std;

int main() {
	int T;
	cin >> T;
	for(int t = 0; t < T; t++) {
		string s;
		const string ok = "possible", ng = "impossible";
		cin >> s;
		reverse(s.begin(), s.end());
		int G, R, W;
		bool flg = true;
		bool fr = false, fg = false;
		R = G = W = 0;
		for(int i = 0; i < s.size(); i++) {
			if(s[i] == 'R') {
				R++;
				fr = true;
			}
			else if(s[i] == 'G') {
				G++;
				R--;
				if(R < 0) flg = false;
				fg = true;
			}
			else {
				if(!fr || !fg) flg = false;
				W++;
				if(G > 0) G--;
			}
		}
		if(R || G) flg = false;
		if(flg)
			cout << ok << endl;
		else
			cout << ng << endl;
	}
}