text: fname = input("Enter file name: ")
  try:
      fh = open(fname)
  except:
      print("File not exist")
      quit()
  lst = list()
  lst2 = list()
  lineStr = ''
  for line in fh:
      lineStr = lineStr + ' '+ line.rstrip()
  
  lst = lineStr.split()
  lst.sort() #必须另起一行，因为sort()方法不会返回值
  
  for str in lst:
      if len(lst2) == 0:
          lst2.append(str)
      elif str != lst2[-1]:
              lst2.append(str)
  
  print(lst2)