# Enter your code here. Read input from STDIN. Print output to STDOUT
from sys import stdin
n = int(raw_input())
array = map(int, stdin.readline().split())

def find_max_count(array, d):
    inc = sum(1 for a in array if (a - d == -1) or (a - d == 0))
    dec = sum(1 for a in array if (a - d ==  1) or (a - d == 0))
    return max(inc, dec)

print max(find_max_count(array, d) for d in array)