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();
            int bus = 0;
            int r = 0;
            int w = 0;
            for(int j=str.length()-1;j>=0;j--){
                char c = str.charAt(j);
                if(c=='W'){
                    if(bus==0){
                        System.out.println("impossible");
                        continue start;
                    }
                    if(bus>w)
                        w++;
                }else if(c=='R'){
                    r++;
                }else if(c=='G'){
                    if(r==0){
                        System.out.println("impossible");
                        continue start;
                    }
                    r--;
                    bus++;
                }
            }
            if(r==0 && w>=bus)
                System.out.println("possible");
            else
                System.out.println("impossible");
        }
    }
}