{

//Initial Template for Java

import java.util.*;

import java.lang.*;

import java.io.*;

class Driverclass

{

public static void main(String args[])

{

Scanner sc = new Scanner(System.in);

int t =sc.nextInt();

while(t-- > 0)

{

ArrayList<ArrayList<Integer>> list = new ArrayList<>();

int nov = sc.nextInt();

int edg = sc.nextInt();

for(int i = 0; i < nov; i++)

list.add(i, new ArrayList<Integer>());

for(int i = 1; i <= edg; i++)

{

int u = sc.nextInt();

int v = sc.nextInt();

list.get(u).add(v);

}

boolean vis[] = new boolean[nov];

for(int i = 0; i < nov; i++)

vis[i] = false;

new Traversal().bfs(0, list, vis, nov);

System.out.println();

}

}

}

}

/*This is a function problem.You only need to complete the function given below*/

//User function Template for Java

/*

*ArrayList<ArrayList<Integer>> list: represent graph containing vertices

and edges between them

*vis[]: boolean array to represent visited vertex

*s: starting vertex

*/

class Traversal

{

static void bfs(int s, ArrayList<ArrayList<Integer>> list, boolean vis[], int nov)

{

LinkedList<Integer> queue =new LinkedList<>();

vis[s]=true;

queue.add(s);

while(queue.size()!=0)

{

int p=queue.poll();

System.out.print(p+" ");

Iterator<Integer> li=list.get(p).listIterator();

while(li.hasNext())

{

int n=li.next();

if(!vis[n])

{

vis[n]=true;

queue.add(n);

}

}

}

}

}