#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main()
{
    long long int n,i,j,k,count=0;
    long long int a[10000];
    cin>>n;
    for(i=0;i<n;i++)
    {
       cin>>a[i];
    }    
    sort(a,a+n);
    int b[1000];
    for(i=0;i<n;i++)
    {
        count=1;
        for(j=0;j<n;j++)
        {
            if((i!=j)&&((a[j]-a[i])==0)||((a[j]-a[i])==1))
            {
                
                count++;
            }    
        }    
        b[i]=count;
    }    
    sort(b,b+n);
    cout<<b[n-1];
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}