/*             deepak gautam
  codechef - algorithmist2 ,codeforce - gautam27
  topcoder- gautam_27      ,spoj - nexus_d
  hackerearth-deepak.gautam.127648 , hackerrank- deepakgautam2701
   */
#include<bits/stdc++.h>
using namespace std;
typedef long long int lli;
#define ff first
#define ss second
#define mp make_pair
#define ph push_back
#define mod 1000000007
#define debug 0
map<lli,int>  ma;
lli arr[100000];

int main()
 {
 	int  n;
 	 cin>>n;
 	 for(int i=0;i<n;i++)
 	  {
 	  	 cin>>arr[i];
 	  	 ma[arr[i]]++;
	   }
	   
	   sort(arr,arr+n);
 int ans=1;
 int l=0;
 for(int i=0;i<n;i++)
 {
 	 for(int j=i+1;j<n;j++)
 	  {
 	  	if(abs(arr[i]-arr[j])<=1)
 	  	{
 	  		ans=max(ans,(j-i+1));
		   }
	   }
 }
 cout<<ans<<endl;
 	
 }