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 start = 0, end = 0;
        int len = 0, maxLen = Integer.MIN_VALUE;
        while(end < a.length) {
            if(a[end] - a[start] <= 1) {
                len++;
                end++;
            } else {
                if(len > maxLen) {
                    maxLen = len;
                }
                if(start == end) {
                    len++;
                    end++;
                } else {
                    start++;
                    len--;
                }
            }
        }
        if(len > maxLen) {
            maxLen = len;
        }
        System.out.println(maxLen);
    }
}