#include<stdio.h>
#include<malloc.h>
#define N 1005
typedef struct Link{
	int data;
	struct Link * next;
	struct Link * fir;
}Link;
Link Pic[N];
int front=0;
int rear=0;
int Check[N];
int Queue[N];
void DFS(Link a[],int fir){
	//printf("%d ",a[fir].data);
	Check[a[fir].data]=1;
	Queue[rear++]=a[fir].data;
	Link * p=a[fir].next;
	while(p){
		if(!Check[p->data]){
			DFS(a,p->data);
		}
		p=p->next;
	}
}
void Init(int n){
	for(int i=0;i<n;i++){
		Pic[i].data=i;
		Pic[i].next=NULL;
		Pic[i].fir=&Pic[i];
	}
}
void CreatePic(Link a[],int n){
	int u,v;
	for(int i=0;i<n;i++){
	   scanf("%d %d",&u,&v);
	   Link * p=(Link * )malloc(sizeof(Link));
	   p->data=v;
	   p->next=NULL;
	   Pic[u].fir->next=p;
	   Pic[u].fir=p;
	   Link * q=(Link * )malloc(sizeof(Link));
	   q->data=u;
	   q->next=NULL;
	   Pic[v].fir->next=q;
	   Pic[v].fir=q;
	}
}
void RollBack(int n){
	front=0;
	rear=0;
	for(int i=0;i<n;i++){
		Check[i]=0;
		Queue[i]=-1;
		Pic[i].next=NULL;
		Pic[i].fir=&Pic[i];
	}
}
int main(){
	int n;
	int k,m,t;
	scanf("%d",&n);
	scanf("%d %d %d",&k,&m,&t);
	while(n--){
		Init(k);
		CreatePic(Pic,m);
		DFS(Pic,t);
		for(int i=0;i<rear;i++){
			i!=rear-1?printf("%d ",Queue[i]):printf("%d\n",Queue[i]);
		}
		RollBack(k);
	}
	return 0;
}