#include <bits/stdc++.h>
#define pb push_back
#define mp make_pair
#define ll long long
#define ull unsigned long long
using namespace std;
int main()
{
	bool testing = false;
	std::ios::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	if(testing)
	{
		freopen("test.txt","rt",stdin);
		//freopen("out.txt","wt",stdout);
	}
	int n;
	cin >> n;
	int arr[n];
	for(int i = 0; i < n; ++i)
	{
		cin >> arr[i];
	}
	sort(arr, arr+n);
	long long max = -1;
	for(int i = 0; i < n; ++i)
	{
        int count = 0;
        int temp = i;
		while(abs(arr[i]-arr[temp+1]) <= 1)
        {
            ++count;
            ++temp;
        }
        if(count > max)
        {
            max = count;
        }
	}
    if(max != 0)
        {
max++;}
	cout << max << endl;
}