class Node: def init(self,val): self.value=val self.left=None self.right=None

class Tree: def init(self): self.root=None

def insert(self,root,val):
    if root is None:
        return Node(val)
    elif root.value>val:
        root.left=self.insert(root.left,val)
    else:
        root.right=self.insert(root.right,val)

    return root

def preOrder(self,root):
    if root is None:
        return 
    print(root.value,end=' ')
    self.preOrder(root.left)
    self.preOrder(root.right)

n=int(input()) nums=list(map(int,input().split())) tree=Tree() tree.root=Node(nums[0]) for num in nums[1:]: tree.insert(tree.root,num) tree.preOrder(tree.root)