#include <iostream>
#include <fstream>
#include <algorithm>
using namespace std;
ofstream fileOut("sortaret.out");
struct element
{
    int val;
    element* next;
};

element* vectorElement[50000];
int starts[50000];
int posStarts=0;

element* aux;

void Descopera(int pos)
{
    if(vectorElement[pos]!=0)
    {
        element* auxy=vectorElement[pos];
        vectorElement[pos]=0;
        while(auxy!= 0)
        {
            fileOut<<auxy->val<<" ";
            Descopera(auxy->val);
            auxy=auxy->next;
        }
    }
}



int main()
{
    ifstream fileIn("sortaret.in");

    int n,m;
    fileIn>>n>>m;
    int x,y;
    for(int i=0;i<m;++i)
    {
        fileIn>>x>>y;
        starts[posStarts]=x;
        ++posStarts;
        if(vectorElement[x]==0)
        {
            vectorElement[x]=new element;
            vectorElement[x]->val=y;
            vectorElement[x]->next=0;
        }
        else
        {
            aux=vectorElement[x];
            while(aux->next !=0)
            {
                aux=aux->next;
            }
            aux->next = new element;
            aux->next->val=y;
            aux->next->next=0;
        }
    }
    sort(starts,starts+posStarts);
    for(int i=0;i<posStarts;++i)
    {
        if(starts[i]!=starts[i+1] and vectorElement[starts[i]]!=0)
        {
            fileOut<<starts[i]<<" ";
            Descopera(starts[i]);
        }
    }
    return 0;
}