import java.util.*;
import java.lang.*;
import java.io.*;

class Ideone{
    public static void main(String[] args) throws Exception{
        // your code goes here
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(br.readLine());
        
        start:for(int i=0;i<n;i++){
            String[] str = br.readLine().split("");
            int bus = 0;
            int g=0;
            int r=0;
            int ww=0;
            boolean w = false;
            for(String st:str){
                if(st.equals("G")){
                    bus++;
                    g++;
                }else if(st.equals("R")){
                    bus--;
                    r++;
                    if(bus<0){
                        System.out.println("impossible");
                        continue start;
                    }
                    w = false;
                }else if(st.equals("W")){
                    w = true;
                    ww++;
                }
            }
            if(w||bus!=0||g>ww){
                System.out.println("impossible");
            }else{
                System.out.println("possible");
            }
        }
    }
}