#include<iostream>
#include<stdio.h>
#include<string.h>
#include<algorithm>
#include<vector>

using namespace std;
typedef pair<int,int> PII;
const int N=501000,M=500100;
int T;
int head[N],elem[M],Next[M];
int index;
int n,m;
vector<PII> edges;

void add(int a,int b){
	elem[index]=b;
	Next[index]=head[a];
	head[a]=index++;
}


int main(){
	memset(head,-1,sizeof(head));
	cin>>T;
	while(T--){
		scanf("%d%d",&n,&m);
		
		while(m--){
			int u,v;
			scanf("%d%d",&u,&v);
			//u->v  v<-u
			edges.push_back({v,u});

		}	
		sort(edges.begin(),edges.end(),greater<PII>());
		
		for(int i=0;i<edges.size();i++){
			add(edges[i].second,edges[i].first);
		}
		for(int i=1;i<=n;i++){
			for(int j=head[i];j!=-1;j=Next[j]){
				printf("%d ",elem[j]);
			}printf("\n");
			head[i]=-1;
		}
		
		edges.clear();
		index=0;
	}
	
	
	return 0;
}