//The best is yet to come...
 #include <iostream>
#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define inf 1000000000000
#define mod 1000000007
#define pb push_back
#define mp make_pair
#define all(v) v.begin(),v.end()
#define S second
#define F first
#define boost1 ios::sync_with_stdio(false);
#define boost2 cin.tie(0);
#define mem(a,val) memset(a,val,sizeof a)
#define endl "\n"
#define maxn 100001

ll a[maxn];

int main()
{
	boost1;boost2;	
	int i,j,n,f=0,x,y,ans=0;
	char ch;
	string s;
	cin>>n;
	for(i=1;i<=n;i++)
	cin>>a[i];
	sort(a+1,a+n+1);
	for(i=1;i<=n;i++)
	{
		for(j=i;j<=n;j++)
		{
			if(a[j]-a[i]<=1)
			ans=max(ans,j-i+1);
		}
	}
	cout<<ans;
	return 0;
}