#include <cstdio>
#include <vector>
using namespace std;

struct nod
{
    int x;
    int y;
};
int n,m;
int viz[100005];
vector < int > graph[50000 * 2 +5];

void citire()
{
    scanf("%d %d",&n,&m);
    for(int i = 0 ; i < n;i++)
    {
        int x,y;
        scanf("%d %d",&x,&y);
        graph[x].push_back(y);
    }

}

void dfs(int i)
{
    printf("%d ",i);
    viz[i] = 1;
    for(int j = 0 ; j < graph[i].size();j++)
    if(viz[graph[i][j]] == 0)
    {
        int v = graph[i][j];
        dfs(v);
    }
}

int main()
{
    freopen("sortaret.in","r",stdin);
    freopen("sortaret.out","w",stdout);
    citire();
    dfs(1);
    return 0;
}