#include<iostream>
#include<string>
using namespace std;

string solve(string str){
    # define OK "possible"
    # define NG "impossible"
    int n = str.size(), w=0, g=0;
    if(str[n-1] != 'R') return NG;
    for(int i=0; i<n; ++i){
        char c = str[i];
             if(c == 'W') ++w;
        else if(c == 'G') ++g;
        else if((--w)<0 || (--g)<0) return NG;
    }
    if(g != 0) return NG;
    return OK;

}

int main(){
	int n;
	cin >> n;
	for(int i=0; i<n; ++i){
		string str;
		cin >> str;
        cout << solve(str) << endl;
	}
}