#include <bits/stdc++.h>
using namespace std;
int main(){
	int t;	cin>>t;
	while(t--){
		string s;	cin>>s;
		int white=0,green=0,red=0;
		bool possible=true;
		for(int i=0;i<(int)s.size();i++){
			if(s[i]=='W')	white++;
			else if(s[i]=='G'){
				green++;
				if(green>white){
					possible=false;
					break;
				}
			}
			else{
				red++;
				if(red>green){
					possible=false;
					break;
				}
			}
		}
		if(red!=green||red==0)	possible=false;
		if(possible)	cout<<"possible"<<endl;
		else 	cout<<"impossible"<<endl;
	}
	return 0;
}