#include <fstream>
#define nmax 100001
using namespace std;
ifstream cin("sortaret.in");
ofstream cout("sortaret.out");
struct coord
{
    int x,y;
}a[nmax];
long long n,m,v[nmax],i;
int dfs(int nod)
{
    int i;
    v[nod]=1;
    cout<<nod<<" ";
    for(i=1;i<=n;i++)
        if(a[i].x==nod&&v[a[i].y]==0)
        dfs(a[i].y);
}
int main()
{
    cin>>n>>m;
    for(i=1;i<=n;i++)
        cin>>a[i].x>>a[i].y;
    dfs(1);
    return 0;
}