#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,ans="possible"; cin >> s;

		int white = 0,red = 0, green = 0;
		for (int i = 0; i < s.size(); i++) {
			if (s[i] == 'G')green++;
			if (s[i] == 'R')red++;
			if (s[i] == 'W')white++;
		}

		if (s[s.size() - 1] != 'R' || s[0] != 'W' || green != red || white < green) {
			cout << "impossible" << endl;
		}
		else 
		{
			white = 0,red = 0, green = 0;
			for (int i = s.size()-1; i >= 0; i--) {
				if (s[i] == 'R') {
					red++;
					if (green > red || white > red) {
						ans = "impossible";
						break;
					}
				}
				if (s[i] == 'G') {
					green++;
					if (green > red || green < white) {
						ans = "impossible";
						break;
					}
				}
				if (s[i] == 'W') {
					green--;
					red--;
				}
			}
			cout << ans << endl;
		}
	}
	return 0;
}