//I am struggling
//Just Not Good at it

#include<bits/stdc++.h>

using namespace std;

#define fast ios_base::sync_with_stdio(false)
#define bfast cin.tie(0)
#define outs(x) cout << x << " "
#define outn(x) cout << x << "\n"
#define sf scanf
#define pf printf
#define nl puts("")
#define psb push_back

typedef long long LL;
typedef vector<int>vii;
typedef vector<LL>vll;

const int mod = 1000007;
const int high = 103;

int ar[high];

int main()
{
	fast;
	int n , i , j , cnt=0;
	while(cin >> n)
	{
		for(i=0; i<n; i++)
		{
			cin >> ar[i];
		}

		sort(ar, ar+n);

		cnt=0;

		int maxi = -1;

		for(i=0; i<n-1; i++)
		{
			cnt=0;

			for(j=i+1; j<n; j++)
			{
				int df = ar[i] > ar[j] ? ar[i] - ar[j] : ar[j] - ar[i];

				if(df <= 1)
				{
					cnt++;
				}
			}

			maxi = max(maxi , cnt);
		}

		cout << maxi+1 << "\n";
	}

	return 0;
}