#include<fstream>
#include<vector>
#include<deque>
#define dim 100001
using namespace std;
vector< vector<int> > mat(dim);
int n,m;
deque<int> dq;
inline void citire()
{
	freopen("ciclueuler.in","r",stdin);
	scanf("%d%d",&n,&m);
	for(;m;--m)
	{
		int x,y;
		scanf("%d%d",&x,&y);
		mat[x].push_back(y);
		mat[y].push_back(x);
	}
}
inline void euler(int k)
{
	freopen("ciclueuler.out","w",stdout);
	dq.push_front(k);
	while( !dq.empty() )
	{
		int x,y;
		x=dq.front();
		if( ! mat[x].size() )
		{
			printf("%d ",x);
			dq.pop_front();
			continue;
		}
		y=mat[x].back();
		mat[x].pop_back();
		dq.push_front(y);
		vector<int>::iterator it;
		for(it=mat[y].begin();it!=mat[y].end();++it)
			if(*it==x)
			{
				mat[y].erase(it);
				break;
			}
	}
}
int main()
{
	citire();
	int ok=0;
	for(int i=1;i<=n;++i)
		if(mat[i].size()%2)
			ok=1;
	if(!ok)
		euler(1);
}