#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[101];

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

	sort(arr, arr+n);

	int counter = 1 , max = -1;

	
	int flag = 0;
	int minnum = arr[0];
	for(int i = 1 ; i < n ; i++)
	{
		if(arr[i] - minnum <= 1)
		{
			counter++;

			if(counter > max) max = counter;
		}
		else
		{
			minnum = arr[i];
			if(counter > max) max = counter;

			counter = 1;
		}
	}

	cout << max << endl;
}