#include <fstream>
#include <iostream>
#include <vector>
#define Nmax 50005

using namespace std;

string file="sortaret";

ifstream f( (file + ".in").c_str() );
ofstream g( (file + ".out").c_str() );

int n, m;
int x, y;
vector <int> v[Nmax];
bool seen[Nmax];

void dfs(int x)
{
    seen[x]=1;
    g << x << " ";
    for (int i = 0, l=v[x].size(); i < l; i++)
    {
        int y=v[x][i];
        if(seen[y] == 1) continue;

        dfs(y);
    }
}

int main()
{
    f >> n >> m;
    for (int i = 1; i <= n; i++)
    {
        f >> x >> y;
        v[x].push_back(y);
    }
    dfs(1);
    return 0;
}