Buggy python submission (verdict: Time Limit Exceeded):
#from statistics import median
#import collections
#aa = collections.Counter(a) # list to list || .most_common(2)で最大の2個とりだせるお a[0][0]
from fractions import gcd
from itertools import combinations,permutations,accumulate # (string,3) 3回
#from collections import deque
from collections import deque,defaultdict,Counter
import decimal
import re
#import bisect
#
#    d = m - k[i] - k[j]
#    if kk[bisect.bisect_right(kk,d) - 1] == d:
#
#
#
# pythonで無理なときは、pypyでやると正解するかも！！
#
#
# my_round_int = lambda x:np.round((x*2 + 1)//2)
# 四捨五入
import sys
sys.setrecursionlimit(10000000)
mod = 10**9 + 7
#mod = 9982443453
def readInts():
  return list(map(int,input().split()))
def I():
  return int(input())
n = I()
A = readInts()
maxA = max(A)
minA = min(A)
ans = -1
for i in range(minA,maxA+1):
    ans = max(ans, A.count(i-1) + A.count(i) + A.count(i+1))
print(ans)


Fixed submission:
#
# Written by NoKnowledgeGG @YlePhan
# ('ω')
#
#import math
#mod = 10**9+7
#import itertools
#import fractions
#import numpy as np
#mod = 10**4 + 7
"""def kiri(n,m):
  r_ = n / m
  if (r_ - (n // m)) > 0:
    return (n//m) + 1
  else:
    return (n//m)"""

""" n! mod m 階乗
mod = 1e9 + 7
N = 10000000
fac = [0] * N
def ini():
  fac[0] = 1 % mod
  for i in range(1,N):
    fac[i] = fac[i-1] * i % mod"""

"""mod = 1e9+7
N = 10000000
pw = [0] * N
def ini(c):
  pw[0] = 1 % mod
  for i in range(1,N):
    pw[i] = pw[i-1] * c % mod"""

"""
def YEILD():
  yield 'one'
  yield 'two'
  yield 'three'
generator = YEILD()
print(next(generator))
print(next(generator))
print(next(generator))
"""
"""def gcd_(a,b):
  if b == 0:#結局はc,0の最大公約数はcなのに
    return a
  return gcd_(a,a % b) # a = p * b + q"""
"""def extgcd(a,b,x,y):
  d = a
  if b!=0:
    d = extgcd(b,a%b,y,x)
    y -= (a//b) * x
    print(x,y)
  else:
    x = 1
    y = 0
  return d"""
# 最大公約数 と 最小公倍数
"""def gcd(a,b):
  if b == 0:
    return a
  return gcd(b, a % b)
def lcm(a,b):
  g = gcd(a,b)
  return (a * b) // g"""

def readInts():
  return list(map(int,input().split()))
mod = 10**9 + 7

def main():
  n = int(input())
  LIST = readInts()
  MAX_ = [0] * (10**5 + 10) # 始めに確保しておく
  for a in LIST:
    for i in range(3):
      MAX_[a+i]+=1 # -1,0,1のように、0,1,2で被るものを考える。
  print(max(MAX_))
if __name__ == '__main__':
  main()

Buggy python submission (verdict: Time Limit Exceeded):
#
# Written by NoKnowledgeGG @YlePhan
# ('ω')
#
#import math
#mod = 10**9+7
#import itertools
#import fractions
#import numpy as np
#mod = 10**4 + 7
"""def kiri(n,m):
  r_ = n / m
  if (r_ - (n // m)) > 0:
    return (n//m) + 1
  else:
    return (n//m)"""

""" n! mod m 階乗
mod = 1e9 + 7
N = 10000000
fac = [0] * N
def ini():
  fac[0] = 1 % mod
  for i in range(1,N):
    fac[i] = fac[i-1] * i % mod"""

"""mod = 1e9+7
N = 10000000
pw = [0] * N
def ini(c):
  pw[0] = 1 % mod
  for i in range(1,N):
    pw[i] = pw[i-1] * c % mod"""

"""
def YEILD():
  yield 'one'
  yield 'two'
  yield 'three'
generator = YEILD()
print(next(generator))
print(next(generator))
print(next(generator))
"""
"""def gcd_(a,b):
  if b == 0:#結局はc,0の最大公約数はcなのに
    return a
  return gcd_(a,a % b) # a = p * b + q"""
"""def extgcd(a,b,x,y):
  d = a
  if b!=0:
    d = extgcd(b,a%b,y,x)
    y -= (a//b) * x
    print(x,y)
  else:
    x = 1
    y = 0
  return d"""
# 最大公約数 と 最小公倍数
"""def gcd(a,b):
  if b == 0:
    return a
  return gcd(b, a % b)
def lcm(a,b):
  g = gcd(a,b)
  return (a * b) // g"""

def readInts():
  return list(map(int,input().split()))
mod = 10**9 + 7

def main():
  n = int(input())
  LIST = readInts()
  LIST = sorted(LIST)
  ans = 1
  pr_ = LIST[0]
  for i in range(1,n):
    cnt = 1
    for j in range(i,n):
      if abs(pr_ - LIST[j]) <= 2:
        cnt += 1
      else:
        ans = max(ans,cnt)
    pr_ = LIST[i]
  print(ans)
  
if __name__ == '__main__':
  main()

Fixed submission:
#
# Written by NoKnowledgeGG @YlePhan
# ('ω')
#
#import math
#mod = 10**9+7
#import itertools
#import fractions
#import numpy as np
#mod = 10**4 + 7
"""def kiri(n,m):
  r_ = n / m
  if (r_ - (n // m)) > 0:
    return (n//m) + 1
  else:
    return (n//m)"""

""" n! mod m 階乗
mod = 1e9 + 7
N = 10000000
fac = [0] * N
def ini():
  fac[0] = 1 % mod
  for i in range(1,N):
    fac[i] = fac[i-1] * i % mod"""

"""mod = 1e9+7
N = 10000000
pw = [0] * N
def ini(c):
  pw[0] = 1 % mod
  for i in range(1,N):
    pw[i] = pw[i-1] * c % mod"""

"""
def YEILD():
  yield 'one'
  yield 'two'
  yield 'three'
generator = YEILD()
print(next(generator))
print(next(generator))
print(next(generator))
"""
"""def gcd_(a,b):
  if b == 0:#結局はc,0の最大公約数はcなのに
    return a
  return gcd_(a,a % b) # a = p * b + q"""
"""def extgcd(a,b,x,y):
  d = a
  if b!=0:
    d = extgcd(b,a%b,y,x)
    y -= (a//b) * x
    print(x,y)
  else:
    x = 1
    y = 0
  return d"""
# 最大公約数 と 最小公倍数
"""def gcd(a,b):
  if b == 0:
    return a
  return gcd(b, a % b)
def lcm(a,b):
  g = gcd(a,b)
  return (a * b) // g"""

def readInts():
  return list(map(int,input().split()))
mod = 10**9 + 7

def main():
  n = int(input())
  LIST = readInts()
  MAX_ = [0] * (10**5 + 10) # 始めに確保しておく
  for a in LIST:
    for i in range(3):
      MAX_[a+i]+=1 # -1,0,1のように、0,1,2で被るものを考える。
  print(max(MAX_))
if __name__ == '__main__':
  main()