output_description: Print the maximum possible value of s.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
      D_1 D_2 ... D_N
attempt: from collections import defaultdict, deque
  import sys, heapq, bisect, math, itertools, string, queue, datetime
  
  sys.setrecursionlimit(10**8)
  INF = float("inf")
  mod = 10**9 + 7
  
  
  def inpl():
      return list(map(int, input().split()))
  
  
  def inpls():
      return list(input().split())
  
  
  N = int(input())
  dd = inpl()
  
  cnt = [0] * 13
  for d in dd:
      cnt[d] += 1
  
  koho = [0]
  ed1 = []
  for d, n in enumerate(cnt):
      if n >= 3:
          print(0)
          sys.exit()
      elif n == 2:
          koho.append(d)
          koho.append(24 - d)
      elif n == 1:
          ed1.append(d)
  
  L = len(ed1)
  ans = 0
  if L != 0:
      for bit in range((1 << L) - 1):
          tmp = koho[:]
          for b in range(L):
              if bit & (1 << b):
                  tmp.append(ed1[b])
              else:
                  tmp.append(24 - ed1[b])
  
          tmp.sort()
          azusa = INF
          azunyan = len(tmp)
          for x in range(1, azunyan):
              azusa = min(tmp[x] - tmp[x - 1], azusa)
          ans = max(azusa, ans)
  else:
      tmp = koho[:]
      azunyan = len(tmp)
      ans = INF
      for x in range(1, azunyan):
          ans = min(tmp[x] - tmp[x - 1], ans)
  
  if ans == 24:
      print(0)
  else:
      print(ans)
  
problem_description: Statement
  
  In CODE FESTIVAL XXXX, there are N+1 participants from all over the world,
  including Takahashi.
  
  Takahashi checked and found that the _time gap_ (defined below) between the
  local times in his city and the i-th person's city was D_i hours. The time gap
  between two cities is defined as follows. For two cities A and B, if the local
  time in city B is d o'clock at the moment when the local time in city A is 0
  o'clock, then the time gap between these two cities is defined to be
  min(d,24-d) hours. Here, we are using 24-hour notation. That is, the local
  time in the i-th person's city is either d o'clock or 24-d o'clock at the
  moment when the local time in Takahashi's city is 0 o'clock, for example.
  
  Then, for each pair of two people chosen from the N+1 people, he wrote out the
  time gap between their cities. Let the smallest time gap among them be s
  hours.
  
  Find the maximum possible value of s.
samples: [{"input": "3\n    7 12 8", "output": "4\n    \n\nFor example, consider the situation where it is 7, 12 and 16 o'clock in each\nperson's city at the moment when it is 0 o'clock in Takahashi's city. In this\ncase, the time gap between the second and third persons' cities is 4 hours.\n\n* * *"}, {"input": "2\n    11 11", "output": "2\n    \n\n* * *"}, {"input": "1\n    0", "output": "0\n    \n\nNote that Takahashi himself is also a participant."}]