#include<iostream>
#include<cmath>
#include<map>
using namespace std;
 
int ar[100];

int partition(int ar[],int p,int r)
{
	int i,pivot,temp,j; 
	pivot=ar[r-1];
	i=p-1;
	
	for(j=p;j<r-1;j++)
	{
		if(pivot>=ar[j])
		{
			i=i+1;
			temp=ar[i];
			ar[i]=ar[j];
			ar[j]=temp;
		}
	}
    temp=ar[i+1];
	ar[i+1]=ar[r-1];
	ar[r-1]=temp;
return i+1;
}

void quickSort(int ar[],int p,int r)
{   int q;
	if(p<r)
	{
		q=partition(ar,p,r);
		quickSort(ar,p,q);
		quickSort(ar,q+1,r);
	}
}

int main()
{
	int n,i,k=0,count=0,max=0,j,diff;
	cin>>n;
	for(i=0;i<n;i++)
	cin>>ar[i];
    quickSort(ar,0,n);
    for(i=0;i<n;i++)
    {   
        j=i+1;
    	while(j<n)
    	{
    		diff=abs(ar[i]-ar[j]);
    		if(diff>1)
    		break;
    		j++;
    		count++;
     }
    	if(max<count+1)
    	max=count+1;
    	count=0;
	}
    cout<<max; 	
	return 0;
}