import java.util.ArrayList;
import java.util.Arrays;
import java.util.Scanner;
import java.util.LinkedList;

public class MainTra {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    String str = sc.nextLine();
    int[] arr = Arrays.stream(str.split(" ")).mapToInt(Integer::valueOf).toArray();

    Solution so = new Solution();
    TreeNode root = so.creatTree(arr,0);
    ArrayList<Integer> res = so.postTraver(root);
    for(int i=0;i<res.size();i++) {
      System.out.print(res.get(i)+" ");
    }
    System.out.println(System.lineSeparator());
  }
}
/****
 *  思想：構(gòu)建樹(shù)的時(shí)候，加入isVisit屬性，全部默認(rèn)為false；
 *  先添加root節(jié)點(diǎn)進(jìn)棧；
 *  執(zhí)行while循環(huán)：（1）彈出棧頂節(jié)點(diǎn)node；（2）如果visit==true;則添加進(jìn)入結(jié)果，回到while循環(huán)；
 *  否則，增加入棧，遵循返過(guò)來(lái)的順序和判空，當(dāng)前節(jié)點(diǎn)的visit賦予true。
 */
class Solution {
  // 先序遍歷
  public ArrayList<Integer> preTraver(TreeNode root) {
    ArrayList<Integer> res = new ArrayList<>();
    LinkedList<TreeNode> stack = new LinkedList<>();
    stack.add(root);
    while(stack.size()>0) {
      TreeNode node = stack.pollLast();
      if(node.isVisit) {
        res.add(node.val);
      }else { //=============================preTraver（模板，唯一差別部分）======
        // 先序遍歷（根左右）進(jìn)棧：右左根的非空元素依次進(jìn)去
        if(node.right!=null) {
          stack.add(node.right);
        }
        if(node.left!=null) {
          stack.add(node.left);
        }
        node.isVisit = true;
        stack.add(node);
      }//==========================================================================
    }
    return res;
  }
  // 中序遍歷
  public ArrayList<Integer> inTraver(TreeNode root) {
    ArrayList<Integer> res = new ArrayList<>();
    LinkedList<TreeNode> stack = new LinkedList<>();
    stack.add(root);
    while(stack.size()>0) {
      TreeNode node = stack.pollLast();
      if(node.isVisit) {
        res.add(node.val);
      }else {
        // 中序遍歷（左根右）進(jìn)棧：右根左的非空元素依次進(jìn)去
        if(node.right!=null) {
          stack.add(node.right);
        }
        node.isVisit = true;
        stack.add(node);
        if(node.left!=null) {
          stack.add(node.left);
        }
      }
    }
    return res;
  }
  // 后序遍歷
  public ArrayList<Integer> postTraver(TreeNode root) {
    ArrayList<Integer> res = new ArrayList<>();
    LinkedList<TreeNode> stack = new LinkedList<>();
    stack.add(root);
    while(stack.size()>0) {
      TreeNode node = stack.pollLast();
      if(node.isVisit) {
        res.add(node.val);
      }else {
        // 后序遍歷（左右根）進(jìn)棧：根右左的非空元素依次進(jìn)去
        node.isVisit = true;
        stack.add(node);
        if(node.right!=null) {
          stack.add(node.right);
        }
        if(node.left!=null) {
          stack.add(node.left);
        }
      }
    }
    return res;
  }
  // 構(gòu)建樹(shù)
  public TreeNode creatTree(int[] arr,int i) {
    if(i>=arr.length) {
      return null;
    }
    TreeNode root = new TreeNode(arr[i]);
    root.left = creatTree(arr,2*i+1);
    root.right = creatTree(arr,2*i+2);
    return root;
  }

}

class TreeNode {
  int val;
  TreeNode left;
  TreeNode right;
  boolean isVisit;

  public TreeNode(int val) {
    this.val = val;
  }
}