#include <iostream>

 #include <cstdlib>

 using namespace std;

 int j;

 struct node {

     int val;

     node *lch;

     node *rch;

 };

 node *creat (node *p, int x) {

     if (p == NULL) {

         node *q = new node;

         q->val = x;

         q->lch = q->rch = NULL;

         return q;

     }

     else {

         if (x < p->val) p->lch = creat (p->lch,x);

         else p->rch = creat (p->rch,x);

         return p;

     }

 }

 void pre_order (node *s) {

     //int j = 0;如果写这里--->每一次进来都是0

     if (s) {

         if (j > )

             cout << " ";

         j++;

         cout << s->val;

         pre_order (s->lch);

         pre_order (s->rch);

     }

 }

 int main() {

     int n,x;

     while (cin >> n) {

         j = ;

         node *root = NULL;

         for (int i = ;i < n; ++i) {

             cin >> x;

             root = creat(root,x);

         }

         pre_order (root);

         cout << endl;

     }

     return ;

 }