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 c1 = 0;
        int c2 = 1;
        int max = 1;
        for (int i = 1; i < n; i++) {
            if (a[i] - a[c1] > 1) {
                c1 = c2;
            } else if (i - c1 + 1 > max) {
                max = i - c1 + 1;
            }
            if (a[i] - a[c2] > 0) {
                c2 = i;
            }
        }
        System.out.println(max);
    }
}