#!/bin/python3

import sys



n = int(input().strip())
a = [int(a_temp) for a_temp in input().strip().split(' ')]
k=0
s=[]
a.sort()

for i in range(n):
    k=0
    t=0
    c=0
    for j in range(n):
        if a[i]-a[j]==0:k+=1
        if a[i]-a[j]==1:t+=1
        if a[i]-a[j]==-1:c+=1
    s.append(k+t)
    s.append(c+k)
    
print(max(s))