#include "bits/stdc++.h"
using namespace std;
#define rep(i, n) for(int i = 0; i < (n); i++)
#define REP(i, s, n) for(int i = (s); i < (n); i++)
#define all(co) begin(co), end(co)
#define maxup(ans, x) (ans = (ans < x ? x : ans))
#define minup(ans, x) (ans = (ans > x ? x : ans))
using P = pair<int, int>;

signed main() {
	int x = 0;
	int n; cin >> n;
	rep(_, n) {
		string s; cin >> s;
		int num = 0;
		int ws = 0;
		for (char c : s) {
			if (c == 'W') { ws++; maxup(ws, num); }
			if (c == 'G') num++;
			if (c == 'R') { num--; ws--; };
			if (num < 0 || num > ws)
				break;
		}
		bool ok = s.substr(s.find_last_of('W')).find('G') != string::npos;
		cout << (num == 0 && ws == 0 && ok ? "possible" : "impossible") << endl;
	}
	//cin >> n;
}