#include <algorithm>
#include <bitset>
#include <cassert>
#include <deque>
#include <queue>
#include <iomanip>
#include <iostream>
#include <iomanip>
#include <iterator>
#include <float.h>
#include <limits>
#include <list>
#include <map>
#include <numeric>
#include <math.h>
#include <set>
#include <sstream>
#include <stack>
#include <stdio.h>
#include <stdlib.h>
#include <string>
#include <time.h>
#include <vector>

using namespace std;

typedef long long ll;
typedef pair<int, int> pi;
typedef vector<int> vi;
typedef vector<bool> vb;
typedef vector<ll> vl;
typedef vector<pi> vp;
typedef vector<string> vs;
typedef set<int> si;
typedef map<int, int> mi;
typedef multimap<int, int> mmi;

int main(int argc, char* argv[])
{
	ios::sync_with_stdio(false);

	int n;
	cin >> n;

	vi a(n);
	for (int i = 0; i < n; ++i)
		cin >> a[i];

	sort(a.begin(), a.end());

	a.push_back(a[n - 1] + 100);

	int res = 0;

	for (int i = 1, prev = 0; i <= n; ++i)
	{
		while (a[i] - a[prev] > 1)
		{
			++prev;
		}
		res = max(res, i - prev + 1);
	}

	cout << res << endl;

	return 0;
}