#include <stdio.h>
#include <algorithm>
#define N_max 100001
using namespace std;
int n,m,x[N_max],y[N_max],E[N_max/2];

int main(){
    int i,j;
    freopen("sortaret.in","r",stdin);
    freopen("sortaret.out","w",stdout);
        scanf("%d%d",&n,&m);
        for(i=0;i<m;i++)scanf("%d%d",&x[i],&y[i]);
        sort(x,x+m);
    j=0;
    for(i=0;i<m;i++)
    if(x[i]!=x[j]){
        sort(y+j,y+i+1);
        j=i+1;}
    if(x[n]!=x[j])sort(y+j,y+n+1);
    for(i=0;i<m;i++){
        if(!E[x[i]])printf("%d ",x[i]);
        if(!E[y[i]])printf("%d ",y[i]);
        E[x[i]]=1; E[y[i]]=1; };
}