#include <fstream>

using namespace std;

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

int x,y,a[101][101],ord[101],k,viz[101],i,n;

void dfs(int x)
{
    int i;
    g<<x<<" ";
  viz[x]=1;
   for(i=1;i<=n;i++)
    if(!viz[i] and a[x][i]==1) dfs(i);

}

int main()
{
     while(f>>x>>y)
     {
        a[x][y]=1;
         if(x>n) n=x;
     }
     for(i=1;i<=n;i++)
        if(!viz[i]) dfs(i);
    return 0;
}