#!/bin/python3

import sys


n = int(input().strip())
a = [int(a_temp) for a_temp in input().strip().split(' ')]
ls = []
for j in range(n):
    num = a[j]
    counteq = 0
    countlow = 0
    counthigh = 0
    for i in a:
        if i == num:
            counteq = counteq + 1
    for i in a:
        if i == num-1:
            countlow = countlow + 1
    for i in a:
        if i == num+1:
            counthigh = counthigh + 1
    if counthigh > countlow:
        final = counteq + counthigh
    else:
        final = counteq + countlow
    ls.append(final)
print (max(ls))