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

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
        int g = Integer.parseInt(bf.readLine());
        while (g-- > 0) {
            HashSet<Integer> ka=new HashSet<>();
            int a = Integer.parseInt(bf.readLine());
            int[] k=new int[a];
            String[] s = bf.readLine().split(" ");
            for(int i=0; i<a; i++){
                k[i]=Integer.parseInt(s[i]);
                ka.add(k[i]);
            }
            int r=(1<<20)-1;
            boolean f=true;
            for(int i=a-1; i>=0; i--){
                r&=k[i];
                if(!ka.contains(r)){
                    f=false;
                    break;
                }
            }
            if(!f) System.out.println(-1);
            else{
                System.out.println(a);
                for(int i=0; i<a; i++) System.out.print(k[i]+" ");
                System.out.println();
            }
        }
    }
}