#include <bits/stdc++.h>
using namespace std;
#define all(a)						a.begin(), a.end()
#define minimum(a)					*min_element(a.begin(), a.end())
#define maximum(a)					*max_element(a.begin(), a.end())
#define cerr1(a)					cerr << "[ " << a << " ]\n"
#define cerr2(a,b)					cerr << "[ " << a << " , " << b << " ]\n"
#define cerr3(a,b,c)				cerr << "[ " << a << " , " << b << " , " << c << " ]\n"
typedef long long ll;
typedef long double ld;
const int INF = 0x3f3f3f3f, MOD = 1e9 + 7;
ll power(ll a, ll n) {ll p = 1;while (n > 0) {if(n%2) {p = p * a;} n >>= 1; a *= a;} return p;}
ll power(ll a, ll n, ll mod) {ll p = 1;while (n > 0) {if(n%2) {p = p * a; p %= mod;} n >>= 1; a *= a; a %= mod;} return p % mod;}
int main(int argc, char const *argv[])
{
	ios::sync_with_stdio(0);
	int n;
	cin >> n;
	std::vector<int> v(n);
	for (int i = 0; i < n; ++i)
	{
		/* code */
		cin >> v[i];
	}
	int Max = INT_MIN;
	for (int i = 0; i < n; ++i)
	{
		/* code */
		int cunt = 0;
		for (int j = 0; j < n; ++j)
		{
			/* code */
			cunt += ((v[j] - v[i]) == 0 || (v[j] - v[i]) == 1); 
		}
		Max = max(Max,cunt);
	}
	for (int i = 0; i < n; ++i)
	{
		v[i] = -v[i];
	}
	for (int i = 0; i < n; ++i)
	{
		/* code */
		int cunt = 0;
		for (int j = 0; j < n; ++j)
		{
			/* code */
			cunt += ((v[j] - v[i]) == 0 || (v[j] - v[i]) == 1); 
		}
	Max = max(Max,cunt);
	}

	cout <<Max;
	return 0;
}