#include <iostream>
#include <iomanip>
#include <sstream>
#include <string>
#include <cmath>
#include <iostream>
using namespace std;

int main() {
	int N;
	cin >> N;

	for (int k = 0;k<N;k++){
		string s;
		cin >> s;
		int WGcounter = 0;
		int GRcounter = 0;
		bool isPossible = true;
		bool isEnd = false;
		for(int i=0;i <(int)s.length();i++){
			if(s[i] == 'G'){
				WGcounter--;
				GRcounter++;
				isEnd = false;
			}else if(s[i] == 'R'){
				if (WGcounter == 0){
					isPossible = false;
						break;
				}else{
					GRcounter--;
					isEnd = true;
				}
			}else{
				WGcounter++;
				isEnd = false;
			}
			if (WGcounter <0 || GRcounter < 0){
				isPossible = false;
				break;
			}
		}

		if (GRcounter != 0 || !isEnd){
			isPossible = false;
		}

		if (isPossible){
			cout << "possible" << endl;
		}else{
			cout << "impossible" << endl;
		}
	}
	return 0;
}