import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int[] a = new int[n];
        for(int i=0; i < n; i++){
            a[i] = in.nextInt();
        }
        
        Arrays.sort(a);
        
        int arr[] = new int[n];
        
        for(int i = 0;i<n;i++){
            int c = 0;
            int k = i;
            while(k<n && a[k] <= a[i]+1 && a[k] >=a[i]){
                c++;
                k++;
            }
            
            arr[i] =c;
        }
        
        int max = 0;
        
        for(int i = 0;i<n;i++){
            max = Math.max(arr[i],max);
        }
        
       
        
        
        
        
        
         
        System.out.println(max);
    }
}