#include <iostream>
#include <vector>
#include <string>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <algorithm>	// require sort next_permutation count __gcd reverse etc.
#include <cstdlib>	// require abs exit atof atoi 
#include <cstdio>		// require scanf printf
#include <functional>
#include <numeric>	// require accumulate
#include <cmath>		// require fabs
#include <climits>
#include <limits>
#include <cfloat>
#include <iomanip>	// require setw
#include <sstream>	// require stringstream 
#include <cstring>	// require memset
#include <cctype>		// require tolower, toupper
#include <fstream>	// require freopen
#include <ctime>		// require srand
#define rep(i,n) for(int i=0;i<(n);i++)
#define ALL(A) A.begin(), A.end()
#define INF 1<<10
using namespace std;

typedef long long ll;
typedef pair<int, int> P;

int cnt[3];
int last[3];

bool solve (string S ){
	memset (cnt, 0, sizeof (cnt ) );
	memset (last, 0, sizeof (last ) );
	map<char,int> col;
	col['W'] = 0, col['G'] = 1, col['R'] = 2;

	bool ok = true;
	rep (i, S.length() ){
		ok &= (cnt[col['G']] <= cnt[col['W']] );
		ok &= (cnt[col['R']] <= cnt[col['G']] );
		cnt[col[S[i]]]++;
		last[col[S[i]]] = i;
	} // end rep
	
	ok &= (cnt[col['R']] != 0 );
	ok &= (cnt[col['R']] == cnt[col['G']] );
	ok &= ((last[col['W']] < last[col['G']] ) && (last[col['W']] < last[col['R']] ) );
	
	return ok;
}

int main()
{
	ios_base::sync_with_stdio(0);

	int T; cin >> T;
	while (T-- ){
		string S = ""; cin >> S;
		bool res = solve (S );
		cout << (res ? "possible" : "impossible" ) << endl;
	} // end while

	return 0;
}