#!/bin/python3

import sys

f=0
k=1
n = int(input().strip())
a = [int(a_temp) for a_temp in input().strip().split(' ')]
if (n>=2 and n<=100):
    for i in range(len(a)):
        if(a[i]<=0 or a[i]>=100):
            f=1
            break
    if(f==0):
        z=1
        a=sorted(a)
        for i in range(0,len(a)):
            k=1
            for j in range(i+1,len(a)):
                if(a[j]-a[i]<=1):
                    k=k+1
                if(k>z):
                    z=k
                
        print(z)