#include<iostream>
#include<cstdio>
#include<cstring>
#include <cstdlib>  
#include <cmath>   
#include<cctype>
#include<string>
#include<set>
#include<iomanip>
#include <map>
#include<algorithm>
#include <functional>
#include<vector>
#include<climits>
#include<stack>
#include<queue>
#include <deque>
#include <climits>
#include <typeinfo>
#include <utility> 
#define all(x) (x).begin(),(x).end()
#define rep(i,m,n) for(int i = m;i < n;++i)
#define pb push_back
#define fore(i,a) for(auto &i:a)
#define rrep(i,m,n) for(int i = m;i >= n;--i)
#define INF INT_MAX/2
using namespace std;
using ll = long long;
using R = double;
using Data = pair<ll, vector<int>>;
const ll MOD = 1e9 + 7;
const ll inf = 1LL << 50;
struct edge { ll from; ll to; ll cost; };

int check(string s) {

	int cnt1 = 0;
	rep(i, 0, s.size()) {
		if (s[i] == 'G')cnt1++;
		else if (s[i] == 'R')cnt1--;
		if (cnt1 < 0)return false;
	}
	if (cnt1 != 0)return false;

	int cnt2 = 0;
	rep(i, 0, s.size()) {
		if (s[i] == 'W')cnt2++;
		else if (s[i] == 'G') {
			cnt2--;
		}
		if (cnt2 < 0)return false;
	}

	reverse(all(s));
	int f = 0;
	rep(i, 0, s.size()) {
		if (s[i] == 'G')f = 1;
		if (s[i] == 'W' && f == 0)return false;
	}
	return true;
}


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

	rep(i, 0, n) {
		string s;
		cin >> s;
		if (check(s))cout << "possible" << endl;
		else cout << "impossible" << endl;
	}
	return 0;
}