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 ai=0; ai < n; ai++){
            a[ai] = in.nextInt();
        }
        
        int maxCount = 0;
        for (int i = 0; i < n; i++) {
            int count = 0;
            for (int j = 0; j < n; j++) {
                int dif = a[i] - a[j];
                
                if (dif <= 1 && dif >= 0) {
                    count++;
                }
            }
            if (count > maxCount) {
                maxCount = count;
            }
        }
        System.out.println(maxCount);
    }
}