#include<iostream>
using namespace std;
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include <algorithm>
#include <limits.h>
#include <iomanip>
#include <map>
#include <set>
#include <list>
#include <deque>
#include <queue>
#include <stack>
#include <bitset>
#include <vector>
#include <numeric>
//setbase - cout << setbase (16); cout << 100 << endl; Prints 64
//setfill -   cout << setfill ('x') << setw (5); cout << 77 << endl; prints xxx77
//setprecision - cout << setprecision (4) << f << endl; Prints x.xxxx
//  INT_MIN Minimum value for a variable of type int.
//  INT_MAX Maximum value for a variable of type int.
//  UINT_MAX Maximum value for a variable of type unsigned int.
//  LONG_MIN Minimum value for a variable of type long.
//  LONG_MAX Maximum value for a variable of type long.
//  ULONG_MAX Maximum value for a variable of type unsigned long.
#define MOD 1000000007
int gcd(int n1, int n2)
{
    if (n2 != 0)
       return gcd(n2, n1%n2);
    else
       return n1;
}
int main(void)
{
	int j,i,n,cnt=0,ma=0;
	cin>>n;int a[n];
	for(i=0;i<n;i++)
		cin>>a[i];
	sort(a,a+n);
	//for(i=0;i<n;i++) cout<<a[i]<<" ";
	//cout<<endl;
	for(i=0;i<n;i++)
	{
		cnt=1;
		for(j=i+1;j<n;j++)
		{
			if(abs(a[i]-a[j])<=1)
			{
				cnt++;//cout<<a[i]<<" "<<a[j]<<endl;
			}
			else break;
		}
		ma=max(ma,cnt);
	}
	ma=max(ma,cnt);
	cout<<ma<<endl;
	return 0;
}