/*
 *
 *	Author: r3gz3n
 *	Description: 
 *	Difficulty: 
 *
 */

#include <bits/stdc++.h>

#define ll long long
#define ull unsigned long long
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define be begin()
#define en end()
#define all(x) (x).begin(),(x).end()
#define alli(a, n, k) (a+k),(a+n+k)
#define REP(i, a, b, k) for(__typeof(a) i = a;i < b;i += k)
#define REPI(i, a, b, k) for(__typeof(a) i = a;i > b;i -= k)
#define REPITER(it, a) for(__typeof(a.begin()) it = a.begin();it != a.end(); ++it)

#define y0 sdkfaslhagaklsldk
#define y1 aasdfasdfasdf
#define yn askfhwqriuperikldjk
#define j1 assdgsdgasghsf
#define tm sdfjahlfasfh
#define lr asgasgash
#define norm asdfasdgasdgsd
#define have adsgagshdshfhds

#define eps 1e-6
#define pi 3.141592653589793

using namespace std;

template<class T> inline T gcd(T x, T y) { if (!y) return x; return gcd(y, x%y); }
template<class T> inline T mod(T x) { if(x < 0) return -x; else return x; }

typedef vector<int> VII;
typedef vector<ll> VLL;
typedef pair<int, int> PII;
typedef vector< pair<int, int> > VPII;
typedef vector< pair<int, PII > > VPPI;

const int MOD = 1e9 + 7;
const int INF = 1e9;

const int MAX = 1e2 + 5;
int a[MAX];

int main(int argc, char* argv[])
{
	ios::sync_with_stdio(false);
	int n;
	cin >> n;
	REP(i, 0, n, 1)
	{
		cin >> a[i];
	}
	sort(alli(a, n, 0));
	int l = 1, ans = 0;
	REP(i, 0, n, 1)
	{
		l = 1;
		REP(j, i+1, n, 1)
		{
			if(a[j] - a[i] <= 1)
				l++;
		}
		ans = max(ans, l);
	}
	cout << ans << endl;
	return 0;
}