#include <fstream>
using namespace std;
ifstream fin("sortaret.in");
ofstream fout("sortaret.out");

int n,x,y,i,j,c[100],a[100][100],nr,k;

int main()
{
    while(fin>>x>>y)
    {
        a[x][0]++;
        a[x][a[x][0]]=y;
        c[y]++;
        if(n<x)
            n=x;
        if(n<y)
            n=y;
    }
    nr++;
    while(n!=k && nr!=0)
    {
        nr=0;
        for(i=1;i<=n;i++)
        {
            if(c[i]==0)
            {
                fout<<i<<' ';
                for(j=1;j<=a[i][0];j++)
                c[a[i][j]]--;
                c[i]=-1;
                k++;
                nr++;
            }
        }
    }
    return 0;
}