#include <iostream>

 #include <vector>

 #include <algorithm>

 #include <queue>

 #include <stack>

 #include <string>

 #include <fstream>

 #include <map>

 #include <set>

 using namespace std;

 struct node {

     int data;

     node *right;

     node *down;

     node(int d = ) : data(d), right(NULL), down(NULL) { }

 };

 struct cmp {

     bool operator() (node *a, node *b) {

         return a->data > b->data;

     }

 };

 void push(node* &head, int k) {

     node *new_node = new node(k);

     new_node->down = head;

     head = new_node;

 }

 node* flatten(node *&root) {

     priority_queue<node*, vector<node*>, cmp> S;

     while (root) {

         S.push(root);

         root = root->right;

     }

     root = NULL;

     node *p;

     while (!S.empty()) {

         node *top = S.top();

         S.pop();

         if (!root) {

             root = top;

             p = top;

         }

         else {

             p->right = top;

             p = p->right;

         }

         if (top->down) S.push(top->down);

     }

     return root;

 }

 void print(node *head) {

     while (head) {

         cout << head->data << " ";

         head = head->right;

     }

 }

 int main() {

     node *root = NULL;

     push( root,  );

     push( root,  );

     push( root,  );

     push( root,  );

     push( ( root->right ),  );

     push( ( root->right ),  );

     push( ( root->right->right ),  );

     push( ( root->right->right ),  );

     push( ( root->right->right ),  );

     push( ( root->right->right->right ),  );

     push( ( root->right->right->right ),  );

     push( ( root->right->right->right ),  );

     push( ( root->right->right->right ),  );

     root = flatten(root);

     print(root);

     return ;

 }