class Node():
 def __init__(self,data=None):
  self.data=data
  self.left=None
  self.right=None
 def insert(self,data):
  if self.data:
   if data<self.data:
    if self.left:
     self.left.insert(data)
    else:
     self.left=Node(data)
   else:
    if self.right:
     self.right.insert(data)
    else:
     self.right=Node(data)
  else:
   self.data=data
 def preorder(self):
  print(self.data,end=' ')
  if self.left:
   self.left.preorder()
  if self.right:
   self.right.preorder()
while 1:
 try:
  a=input()
  b=list(map(int,input().split()))
  c=Node()
  for d in b:
   c.insert(d)
  c.preorder()
  print()
 except:
  break