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[] arr = new int[n];
        for(int a_i=0; a_i < n; a_i++){
            arr[a_i] = in.nextInt();
        }
        Arrays.sort(arr);
        int m=0;
        int max=0;
        int i=0,j=0;
        while(j<n){
            while(arr[j]-arr[i]>1){
                i++;
                m--;
                if(m<0){
                    m=0;
                }
            }
            if(arr[j]-arr[i]<=1){
                m++;
                if(m>max){
                    max=m;
                }
            }
            j++;
        }
        System.out.println(max);
    }

}