#include <bits/stdc++.h>
using namespace std;

// 基本テンプレート
struct cww{cww(){ios::sync_with_stdio(false);cin.tie(0);}}star;
#define P(x) cout << (x) << endl
#define p(x) cout << (x)
#define all(c) (c).begin(), (c).end()
#define rall(c) (c).rbegin(), (c).rend()
#define mat(type, c, m, n) vector<vector<type>> c(m, vector<type>(n));for(auto& r:c)for(auto& i:r)cin>>i;
#define rep(i,a,n) for(int i=(a), i##_len=(n); i<i##_len; ++i)
#define rrep(i,a,n) for(int i=(a); i>n; --i)
#define each(x,y) for(auto &(x):(y))
#define perm(c) sort(all(c));for(bool c##p=1;c##p;c##p=next_permutation(all(c)))
#define cauto const auto&
#define UNIQUE(v) v.erase( unique(all(v)), v.end() );
#define len(x) ((int)(x).size())
#define length(a)   (sizeof(a)/sizeof(a[0]))
inline void print() {cout << endl;}
template <class H, class... T> inline void print(H h, T... t){cout << h << " ";print(t...);}
#define dbg(v) for(auto i : v) cout << i << " "; cout << endl;

// 型
typedef long long ll;
typedef vector<int> vi;
typedef vector<double> vd;
typedef vector<long long> vll;
typedef vector<string> vs;

// 4近傍
//int dy[]={0, 1, 0, -1};
//int dx[]={1, 0, -1, 0};

// 8近傍
//constexpr int dy[]={0,0,1,-1,1,1,-1,-1};
//constexpr int dx[]={1,-1,0,0,1,-1,1,-1};

 ll mod = (int)1e9 + 7;

// 定数
#define PI acos(-1.0)
constexpr int EPS = (1e-9);
constexpr int INF = 100000000;


void f(){
	int t; cin >> t;

	rep(i, 0, t) {
		string s; cin >> s;

		if ((count(all(s), 'R') == 1 && s[len(s) - 2] != 'G')) P("impossible");
		else if (len(s) < 3) P("impossible");
		else if (s[0] != 'W') P("impossible");
		else if (s.back() != 'R') P("impossible");
		else if (count(all(s), 'G') != count(all(s), 'R')) P("impossible");
		else if (s.rfind('W') > s.rfind('G')) P("impossible");
		else {
			int cnt = 0;
			rrep(i, len(s) - 1, -1) {
				if (s[i] == 'R') ++cnt;
				if (s[i] == 'G') --cnt;
				if (cnt < 0) break;
			}
			if (cnt != 0) P("impossible");
			else P("possible");
		}
	}
}


int main() {
//	cout << setprecision(12) << fixed;

	f();

	return 0;
}