#include<cstdio>
#include<vector>
using namespace std;
int n,i,j,m,nrv[100001],cate,vec[500001],q[500001],pp,st[500001],numar;
vector<int> v[100001];
int main ()
{
freopen("ciclueuler.in","r",stdin);
freopen("ciclueuler.out","w",stdout);
scanf("%d%d",&n,&m);
int x,y,poz,maxim=0;
for(i=1;i<=m;i++)
    {
    scanf("%d%d",&x,&y);
    v[x].push_back(y);
    v[y].push_back(x);
    nrv[x]++;
    nrv[y]++;
    }
st[++cate]=1;
while(cate!=0)
    {
    y=st[cate];
    x=0;
    if(v[y].size()>=1)
        x=v[y][v[y].size()-1];
    if(x!=0)
        {
        v[y].pop_back();
        for(i=0;i<v[x].size();i++)
            if(v[x][i]==y)
                {
                for(j=i;j<v[x].size()-1;j++)
                    v[x][j]=v[x][j+1];
                v[x].pop_back();
                break;
                }
        st[++cate]=x;
        }
    else
        {
        if(numar<m)
            printf("%d\n",st[cate]);
        cate--;
        numar++;
        }
    }
return 0;
}