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

typedef complex<double> P;
int main(){
	string s;
	cin >> s;
	while( cin >> s ){
		vector< pair<int,char> > S;
		for(int i = 0 ; i < s.size() ; i++)
			S.push_back({i,s[i]});
		int canskip[1010] = {};
		while( S.size() ){
			if( S.back().second == 'W' ){
				if( canskip[S.back().first] == 0 ) break; 
				else S.pop_back();
			}else if( S.back().second == 'R'){
				int f = 0;
				for(int i = S.size() - 1 ; i >= 0 ; i--){
					if( S[i].second == 'G'){
						for(int j = 0 ; j <= i ; j++)
							canskip[S[j].first] = true;

						S.pop_back();
						S.erase(S.begin()+i);

						f = 1;
						break;
					}
				}		

				if(!f) break;
			}else{
				break;
			}

		}
		if( S.size() == 0 ) cout << "possible" << endl;
		else cout << "impossible" << endl;
	}
}