#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000001

int main(){	
	
	int _t;
	cin>>_t;
	
	rep(_,_t){
		string s;
		cin>>s;
		
		reverse(s.begin(),s.end());
		
		int a = 0;
		int t =0;
		rep(i,s.size()){
			if(s[i]=='R')t++, a++;
			if(s[i]=='G')a--;
			
			if(a<0)break;
		}
		if(t*3>s.size())a = -1;
		if(a<0)cout<<"impossible"<<endl;
		else cout<<"possible"<<endl;
	}
	
	return 0;
	
}