#include<fstream>
using namespace std;
ifstream f("ciclueuler.in");
ofstream fout("ciclueuler.out");
struct  nod{
	int inf;
	nod* adr;
}*v[100001];
int n,m,sf,V,E[100001],j;
void citire()
{
	f>>n>>m;
	for(int i=1;i<=m;i++)
	{
		int x,y;
		f>>x>>y;
		nod *p=new nod;
		p->inf=y;
		p->adr=v[x];
		v[x]=p;
		p=new nod;
		p->inf=x;
		p->adr=v[y];
		v[y]=p;
	}
}
void euler(int I)
{
	for(nod*p=v[I];p->adr;p=p->adr)
	{
		V=p->inf;
		v[I]=p->adr;
		
		for(nod *q=v[V];q->adr;q=q->adr)
			if(q->inf==I)
			{q->inf=q->adr->inf;
				q->adr=q->adr->adr;
			}
		sf++;
		for(j=sf;j>I;j--)
			E[j]=E[j-1];
		E[++I]=V;
		euler(I);
		
	}
}
main()
{
	citire();
	E[1]=1;
	euler(1);
	return 0;
}