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 count = 0;
        int maxCount = Integer.MIN_VALUE;
        for(int i = 0 ; i < n-1 ; i++) {
            for(int j = n-1 ; j > i ; j--) {
                if(A[j] - A[i] <= 1) {
                    count = j-i+1;
                    break;
                }
            }
            maxCount = Math.max(maxCount,count);
        }
        System.out.println(maxCount);
    }
}