#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <cmath>
#include <set>
using namespace std;


void solve(){
	char c[2000];
	scanf("%s", c);
	string s = c;

	deque<int> w;
	deque<int> g;
	deque<int> r;

	int n = s.size();
	for(int i=0; i<n; i++){
		if(s[i] == 'W'){
			w.push_back(i);
		}else if(s[i] == 'G'){
			if(w.size() > 0){
				w.pop_front();
				g.push_back(i);
			}else{
				cout << "impossible" << endl;
				return;
			}
		}else if(s[i] == 'R'){
			if(g.size() > 0){
				g.pop_front();
				r.push_back(i);
			}else{
				cout << "impossible" << endl;
				return;
			}
		}
	}

	if(g.size()>0){
		cout << "impossible" << endl;
	}else if(w.size()>0 && r.size()>0 && w.back() > r.back()){
		cout << "impossible" << endl;
	}else{
		cout << "possible" << endl;
	}

}

int main(){
	int T;
	cin >> T;
	while(T--){
		solve();
	}

}