#include <fstream>
#include <vector>

using namespace std;

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

int n, m;
vector <int> Muchii[50001];
bool vizitat[50001];
int rez[50001], k;

void DFS(int nod)
{
    int vecin;
    vizitat[nod] = 1;
    rez[++k] = nod;
    for (int i = 0; i < Muchii[nod].size(); ++i)
    {
        vecin = Muchii[nod][i];
        if (!vizitat[vecin])
            DFS(vecin);
    }
}

void citire()
{
    int x, y;
    in >> n >> m;
    for (int i = 1; i <= n; ++i)
    {
        in >> x >> y;
        Muchii[x].push_back(y);
    }
    DFS(1);
}

int main()
{
    citire();
    for (int i = 1; i <= k; ++i)
        out << rez[i] << " ";
    return 0;
}