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 max = 0;
        for (int currentStart = 0; currentStart < n; currentStart++) {
            int current = 0;
            while (current < n && a[current] - a[currentStart] <= 1) {
                current++;
            }
            if (current - currentStart > max) {
                max = current - currentStart;
            }
        }
        System.out.println(max);
    }
}