class TreeNode:
    def __init__(self, value):
        self.value = value
        self.left = None
        self.right = None

def build_tree(numbers):
    root = TreeNode(numbers[0])
    for num in numbers[1:]:
        current = root
        while True:
            if num < current.value:
                if current.left:
                    current = current.left
                else:
                    current.left = TreeNode(num)
                    break
            else:
                if current.right:
                    current = current.right
                else:
                    current.right = TreeNode(num)
                    break
    return root

def preorder_traversal(node):
    if not node:
        return
    print(node.value, end=' ')
    preorder_traversal(node.left)
    preorder_traversal(node.right)

try:
    while True:
        N = int(input())
        numbers = list(map(int, input().split()))
        tree_root = build_tree(numbers)
        preorder_traversal(tree_root)
        print()
except EOFError:
    pass