#include<iostream>
#include<string>
using namespace std;
bool possible(string s){
	int w, g, r, lw, lg, lr;
	w = g = r = 0;
	lw, lg, lr = -1;
	for (int j = 0; j < s.size(); j++){
		switch (s[j]){
		case 'W':
			w++; lw = j;
			break;
		case 'G':
			if (w == 0) return false;
			w--; g++; lg = j;
			break;
		case 'R':
			if (g == 0) return false;
			g--; r++; lr = j;
			break;
		}
	}
	if (g != 0 || r == 0) return false;
	if (lw < lg && lg < lr) return true;
	return false;
}
int main(){
	int n; cin >> n;
	for (int i = 0; i < n; i++){
		string s; cin >> s;
		cout << (possible(s) ? "possible" : "impossible") << endl;
	}
	return 0;
}