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];
        int[] b = new int[101];
        for(int a_i=0; a_i < n; a_i++){
            a[a_i] = in.nextInt();
            b[a[a_i]]++;
        }
        in.close();
        int[] sums = new int[101];
        sums[0] = 0;
        for (int i = 1; i < sums.length; i++) {
            sums[i] = b[i - 1] + b[i];
        }
        int max = max(sums);
        //int next = (b[max - 1] >= b[max + 1])?b[max - 1]:b[max + 1];
        System.out.println(max);
    }
    
    public static int max(int[] arr) {
        int max = 0;
        for (int item : arr) {
            if (item > max) max = item;
        }
        return max;
    }
}