output_description: Print the maximum possible number of i such that a_i=X.
  
  * * *
input_description: The input is given from Standard Input in the following format:
  
      
      
      N
      a_1 a_2 .. a_N
attempt: n = int(input())
  l = list(map(int, input().split()))
  l.sort()
  lcount = []
  count = 0
  now = l[0]
  for i in range(n):
      if now == l[i]:
          count += 1
      else:
          lcount.append([count, now])
          count = 1
          now = l[i]
  lcount.append([count, now])
  if len(lcount) == 1:
      print(n)
  elif len(lcount) == 2:
      l1 = lcount[0][0]
      l2 = lcount[1][0]
      if lcount[1][1] - lcount[0][1] == 1:
          print(l1 + l2)
      else:
          print(max(l1, l2))
  else:
      count = 0
      for i in range(1, len(lcount) - 1):
          scount = 0
          scount += lcount[i][0]
          if lcount[i][1] - lcount[i - 1][1] == 1:
              scount += lcount[i - 1][0]
          if lcount[i][1] - lcount[i + 1][1] == -1:
              scount += lcount[i + 1][0]
          if scount > count:
              count = scount
      count1 = lcount[0][0]
      if lcount[1][1] - lcount[0][1] == 1:
          count1 += lcount[1][0]
      count2 = lcount[-1][0]
      if lcount[-2][1] - lcount[-1][1] == -1:
          count2 += lcount[-2][0]
      print(max(count, count1, count2))
  
problem_description: Statement
  
  You are given an integer sequence of length N, a_1,a_2,...,a_N.
  
  For each 1≤i≤N, you have three choices: add 1 to a_i, subtract 1 from a_i or
  do nothing.
  
  After these operations, you select an integer X and count the number of i such
  that a_i=X.
  
  Maximize this count by making optimal choices.
samples: [{"input": "7\n    3 1 4 1 5 9 2", "output": "4\n    \n\nFor example, turn the sequence into 2,2,3,2,6,9,2 and select X=2 to obtain 4,\nthe maximum possible count.\n\n* * *"}, {"input": "10\n    0 1 2 3 4 5 6 7 8 9", "output": "3\n    \n\n* * *"}, {"input": "1\n    99999", "output": "1"}]