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 scan = new Scanner(System.in);
        int n = scan.nextInt();
        int[] a = new int[n];
        
        for(int i=0; i < n; i++){
            a[i] = scan.nextInt();
            
        }
        int smaller = 0;
        int max = 0, count = 0;
        for (int i = 0; i < n; i++) {
        	smaller = a[i];
        	count = 1;
        	for (int j = 0; j < n; j++) {
        		if (i == j) {
        			continue;
        		}
        		if (Math.abs(a[i]-a[j]) <= 1 && a[j] >= smaller) {
        			count++;
        		}
        	}
        	
        	if (count > max) {
        		max = count;
        	}
        }
        System.out.println(max);
        scan.close();
    }
}