#include <iostream>
#include <fstream>
#include <queue>

using namespace std;

ifstream fin("sortaret.in");
ofstream fout("sortaret.out");

unsigned short int n, fr[50001];
unsigned int m;

queue<int> coada;

int main()
{
    fin >> n >> m;
    unsigned short int x, y;
    for(int i = 1; i <= m; i++){
        fin >> x >> y;
        if(fr[x] == 0) {
            fr[x] = 1;
            coada.push(x);
        }
        if(fr[y] == 0) {
            fr[y] = 1;
            coada.push(y);
        }
        if(coada.size() == n)
            break;
    }

    for(int i = 1; i <= n; i++) {
        fout << coada.front() << ' ';
        coada.pop();
    }
    return 0;
}