#include<cstdio>
#include<iostream>
#include<algorithm>
#include<string>
#include<queue>
#include<vector>
#include<functional>
#include<cmath>
#include<map>
#include<stack>
#include<set>
#include<numeric>
#include<limits>

#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()

using namespace std;
typedef long long ll;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef pair<ll, string> pls;

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

	for (int i = 0; i < N; i++)
	{
		string s; cin >> s;
		int red = 0, green = 0, white = 0;
		bool flag = true;
		if (s.size() < 3) {
			cout << "impossible" << endl;
			continue;
		}
		for (int i = 0; i < s.size(); i++) {
			if (s[i] == 'G') {
				if (green >= red && white >= 1) {
					green++;
					white--;
					flag = true;
				}
				else {
					cout << "impossible" << endl;
					break;
				}
			}
			else if (s[i] == 'R') {
				if (green >= red + 1) {
					red++;
				}
				else {
					cout << "impossible" << endl;
					break;
				}
			}
			else {
				white++;
				flag = false;
			}

			if (i == s.size() - 1) {
				if (green == red && white >= 0 && flag) {
					cout << "possible" << endl;
				}
				else
					cout << "impossible" << endl;
			}
		}
	}
	return 0;
}