import java.util.*;

public class Solution2 {

    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 count = 0, temp = 0;
        for (int i = 0; i < n; i++) {
            temp = 0;
            for (int j = i; j < n; j++) {
                if (a[j] - a[i] <= 1)
                    temp++;
            }
            if (temp > count)
                count = temp;
        }
        System.out.println(count);
    }
}