package com.hackerrank;

import java.util.ArrayList;

import java.util.Collections;

import java.util.List;

import java.util.Scanner;

class PickingNumbers {

public static void main(String[] args) {

Scanner scanner = new Scanner(System.in);

int n = scanner.nextInt();

ArrayList<Integer> arrList = new ArrayList<>(n);

int i = 0;

while (i < n) {

arrList.add(scanner.nextInt());

i++;

}

System.out.println(pickingNumbers(arrList));

}

public static int pickingNumbers(List<Integer> a) {

int aLen = a.size();

Collections.sort(a);

if (a.get(0).equals(a.get(aLen - 1)))

return aLen;

int maxCount = 0;

// Linear Search, O(n)

int minNumb = a.get(0);

int count = 1;

for (int i = 0; i < aLen - 1; i++) {

if (Math.abs(a.get(i + 1) - minNumb) <= 1) {

count++;

} else {

minNumb = a.get(i + 1);

if (count > maxCount)

maxCount = count;

count = 1;

}

}

if (count > maxCount)

maxCount = count;

return maxCount;

}

}