#include <bits/stdc++.h>
#define sz(x) ((int) (x).size())
#define lld long long int
#define MAX(a,b) (((a)>(b))?(a):(b))

using namespace std;

template<class T> string toString(T x) {ostringstream ss; ss << x; return ss.str();}
const int inf = 1000000000;

int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);

	int n; cin >> n;
	int arr[n];
	for(int i = 0; i < n; i++) 
	{
		cin >> arr[i];	
	}


	sort(arr, arr+n);

	

	int i = 0;

	int max_length = 1;
	while(i < n - 1)
	{
		int num1 = arr[i];
		i += 1;
		int length = 1;
		while(abs(arr[i] - num1) <= 1)
		{
			length += 1;
			i += 1;
		}

		if(length > max_length)
			max_length = length;
	}
	
	cout << max_length << endl;

    return 0;
}