output_description: Print the number of choices of the integer K that make the number of problems
  for ARCs and the number of problems for ABCs the same.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
      d_1 d_2 ... d_N
attempt: N = int(input())
  d = [int(i) for i in input().split()]
  #  N = 6
  #  d = list(sorted([9, 1, 4, 4, 6, 7]))
  #  N = 8
  #  d = sorted([9, 1, 14, 5, 5, 4, 4, 14])
  #  N = 14
  #  d = sorted(
  #      [
  #          99592,
  #          10342,
  #          29105,
  #          78532,
  #          83018,
  #          11639,
  #          92015,
  #          77204,
  #          30914,
  #          21912,
  #          34519,
  #          80835,
  #          100000,
  #          1,
  #      ]
  #  )
  l = len(d) // 2
  boundary = d[l - 1]
  next_d = boundary
  boundary_cnt = 0
  for i in d[l:]:
      if i == boundary:
          boundary_cnt += 1
          if boundary > 2:
              next_d = boundary
              break
      elif i > boundary:
          next_d = i
          break
  print(next_d - boundary)
  
problem_description: Statement
  
  Takahashi made N problems for competitive programming. The problems are
  numbered 1 to N, and the difficulty of Problem i is represented as an integer
  d_i (the higher, the harder).
  
  He is dividing the problems into two categories by choosing an integer K, as
  follows:
  
    * A problem with difficulty K or higher will be _for ARCs_.
    * A problem with difficulty lower than K will be _for ABCs_.
  
  How many choices of the integer K make the number of problems for ARCs and the
  number of problems for ABCs the same?
samples: [{"input": "6\n    9 1 4 4 6 7", "output": "2\n    \n\nIf we choose K=5 or 6, Problem 1, 5, and 6 will be for ARCs, Problem 2, 3, and\n4 will be for ABCs, and the objective is achieved. Thus, the answer is 2.\n\n* * *"}, {"input": "8\n    9 1 14 5 5 4 4 14", "output": "0\n    \n\nThere may be no choice of the integer K that make the number of problems for\nARCs and the number of problems for ABCs the same.\n\n* * *"}, {"input": "14\n    99592 10342 29105 78532 83018 11639 92015 77204 30914 21912 34519 80835 100000 1", "output": "42685"}]