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

public class Solution {
    
    static int localmax = 0;
	static int answer = 0;

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] a = new int[n];
        int[] b = new int[n];
        for(int a_i=0; a_i < n; a_i++){
            a[a_i] = sc.nextInt();
            b[a_i] = 0;
        }
        Arrays.sort(a);
        
        for(int i = 0; i< n; i++){
        	for(int j = i; j < n; j++){
        		if (a[j] <= a[i] + 1){
        			localmax++;
        		}
        	}
        	answer = Math.max(localmax, answer);
        	localmax = 0;
        }
        System.out.println(answer); 
        
    }
}