#include <iostream>
#include <fstream>
#include <vector>
#include <stack>
#include <queue>
#define nmax 50002
using namespace std;

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


vector < bool > used (nmax, false);
vector < vector < int > > gf;
queue <int> stk;
void dfs(int x)
{
    used[x] = true;
    stk.push(x);
    for(int i=0; i<gf[x].size(); i++)
    {
        if (!used[gf[x][i]])
            dfs(gf[x][i]);
    }
}

int main()
{
    int n, m, x, y;
    f >> n >> m;
    gf.resize(n+1);

    for(int i=1; i<=n; i++)
    {
        f >> x >> y;
        gf[x].push_back(y);
    }

    dfs(1);

    while(!stk.empty())
    {
        g << stk.front() << " ";
             stk.pop();
    }
    return 0;
}