output_description: Print the maximum value in a line.
input_description: The first line contains an integer $n$. In the following $n$ lines, $R_t$ ($t
  = 0, 1, 2, ... n-1$) are given in order.
attempt: # region
  import sys
  import itertools
  
  DEBUG = True if (len(sys.argv) > 1 and sys.argv[1] == "DEBUG") else False
  
  
  def dp(value):
      if DEBUG:
          print(value)
      return
  
  
  def input_text(split=" "):
      # 入力
      result = []
      while True:
          try:
              row = list(
                  map(lambda x: int(x) if x.isdecimal() else x, input().split(split))
              )
              result.append(row)
          except EOFError:
              break
      return result
  
  
  # endregion
  it = input_text()
  
  r = list(itertools.chain.from_iterable(it[1:]))
  r_min = sys.maxsize
  diff_max = -sys.maxsize
  
  if len(r) == 0:
      print(0)
      sys.exit()
  
  for rj in r:
      dif = rj - r_min
      if diff_max < dif:
          diff_max = dif
      if rj < r_min:
          r_min = rj
  
  print(diff_max)
  
problem_description: Maximum Profit
  
  You can obtain profits from foreign exchange margin transactions. For example,
  if you buy 1000 dollar at a rate of 100 yen per dollar, and sell them at a
  rate of 108 yen per dollar, you can obtain (108 - 100) × 1000 = 8000 yen.
  
  Write a program which reads values of a currency $R_t$ at a certain time $t$
  ($t = 0, 1, 2, ... n-1$), and reports the maximum value of $R_j - R_i$ where
  $j > i$ .
samples: [{"input": "6\n    5\n    3\n    1\n    3\n    4\n    3", "output": "3"}, {"input": "3\n    4\n    3\n    2", "output": "-1"}]