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())
  a=list(map(int,input().split()))
  
  l=sorted(a)
  
  # N=10
  # l=[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
  if N>=10**3:
      math.
  
  
  ans=1
  
  for i in range(N):
      if i>=1 and l[i]==l[i-1]:
          continue
      else:
          t=l[i]
          for j in range(N-i):
              c=l[i+j]
              if abs(c-t)<=2:
                  continue
              else:
                  _ans=j
                  if _ans>ans:
                      ans=_ans
                  else:
                      pass
                  break
  print(ans)
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"}]