#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <queue>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;

static const double EPS = 1e-8;
static const double PI = 4.0 * atan(1.0);
static const double PI2 = 8.0 * atan(1.0);

#define REP(i,n)	for(int i=0;i<(int)n;++i)
#define ALL(c)		(c).begin(),(c).end()
#define CLEAR(v)	memset(v,0,sizeof(v))
#define MP(a,b)		make_pair((a),(b))
#define ABS(a)		((a)>0?(a):-(a))
#define FOR(i,s,n)	for(int i=s;i<(int)n;++i)

void solve() {
	string S;
	cin >> S;
	bool res = S[S.length() - 1] == 'R';
	int j, k;
	for (int i = S.length() - 1; i >= 0; --i) {
		if (S[i] == 'R') {
			for (j = i - 1; j >= 0; --j) if (S[j] == 'G') {
				for (k = j - 1; k >= 0; --k) if (S[k] == 'W') {
					S[j] = 'g';
					break;
				}
				break;
			}
			if (j == -1 || k == -1) res = false;
		}
		else if (S[i] == 'G') {
			res = false;
			break;
		}
	}
	int w = 0;
	bool f = false;
	REP(i, S.length()) {
		if (S[i] == 'W') {
			++w;
			f = true;
		}
		else if (S[i] == 'g') {
			--w;
			f = false;
			if (w < 0) break;
		}
	}
	res &= (w >= 0);
	res &= !f;
	cout << (res ? "possible" : "impossible") << endl;
}

int main(int argc, char **argv) {
	int T;
	cin >> T;
	REP(i, T) solve();
	return 0;
}