# !/bin/python3

import sys

n = int(input().strip())
a = [int(a_temp) for a_temp in input().strip().split(' ')]
c = 0
for i, x in enumerate(a):
    temp1 = 0
    temp2 = 0
    for y in a[i + 1:]:
        if -1 <= x - y <= 0:
            temp1 += 1
        if 0 <= x - y <= 1:
            temp2 += 1
    if temp1 > c:
        c = temp1
    if temp2 > c:
        c = temp2

print(c+1)