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 a_i=0; a_i < n; a_i++){
            a[a_i] = in.nextInt();
        }
        Arrays.sort(a);
        int mc = 1, c = 1;
        int start = 0;
        for(int i=1; i<n; i++){
           // System.out.println(c);
                if(a[i] - a[start] > 1){
                    start = start+1;
                    i--;
                    if(c != 1)
                        c--;
                   // System.out.println(c + " " + a[i]);
                }
            else{
                if(i != start) c++;
            }
            if(c > mc)
                        mc = c;
            }
            
        
        System.out.println(mc);
        
    }
}