#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <cmath>
#include <stdio.h>
#include <queue>
#include <deque>
#include <cstdio>
#include <set>
#include <map>
#include <bitset>
#include <stack>
#include <cctype>
using namespace std;
int main() {
	int t;
	cin >> t;
	for (int i = 0; i < t; i++) {
		string s;
		cin >> s;
		int w = 0, g = 0, r = 0;
		int w1 = 0;
		bool n = true;
		for (int j = 0; j < s.size(); j++) {
			if (s[j] == 'W') {
				w++;
				w1++;
			}
			else if (s[j] == 'G') {
				g++;
				w1 = 0;
			}
			else {
				r++;
			}
			if (w < g || g < r) {
				n = false;
			}
		}
		if (n && g == r && w1 == 0) {
			cout << "possible" << endl;
		}
		else {
			cout << "impossible" << endl;
		}
	}
}