#include<fstream>
#include<vector>
#include<queue>
using namespace std;

int n,m,dads[1310];
vector<int>a[1310];
queue<int>q;

int main()
{
   fstream in("lottery.in");
   ofstream out("lottery.out");

   int i,x,y;

   in>>n;

   for(i=1;i<=n;i++)
   {
      in>>x>>y;
      a[x].push_back(y);
      dads[y]++;

      if(x>m) m=x;
      if(y>m) m=y;
   }

   for(i=1;i<=m;i++)
      if(dads[i]==0)
         q.push(i);

   x=q.front();
   q.pop();
   out<<x;
   for(i=0;i<a[x].size();i++)
   {
      dads[a[x][i]]--;
      if(dads[a[x][i]]==0)
         q.push(a[x][i]);
   }

   while(!q.empty())
   {
      x=q.front();
      q.pop();

      out<<' '<<x;

      for(i=0;i<a[x].size();i++)
      {
         dads[a[x][i]]--;
         if(dads[a[x][i]]==0)
            q.push(a[x][i]);
      }
   }

   out<<endl;

   return 0;
}