#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define mod 1000000007
#define eps 1e-13
#define PI 3.14159265359
#define INF 1000000011
#define INFLL 1000000000000000011LL
#define space printf(" ")
#define endl printf("\n")
#define vi vector<int>
#define vll vector<long long>
#define vc vector<char>
#define vs vector<string>
#define pii pair<int, int>
#define pll pair<long long, long long>
#define pil pair<int, long long>
#define pli pair<long long, int>
#define pcc pair<char, char>
#define mp make_pair
#define F first
#define S second
#define pb(x) push_back(x)
#define fo(i,a,n) for(i = (a); i < (n); i++)
#define foi(i,a,n) for(int i = (int)(a); i < (int)(n); i++)
#define foll(i,a,n) for(long long i = (long long)(a); i < (long long)(n); i++)
#define sd(x) scanf("%d", &(x))
#define pd(x) printf("%d", (x))
#define pdn(x) printf("%d\n", (x))
#define slld(x) scanf("%lld", &(x))
#define plld(x) printf("%lld", (x))
#define plldn(x) printf("%lld\n", (x))
#define sllf(x) scanf("%llf", &(x))
#define pllf(x) printf("%.9llf", (x))
#define pllfn(x) printf("%.9llf\n", (x))
#define sch(x) scanf("%c", &(x))
#define pch(x) printf("%c", (x))
#define pchn(x) printf("%c\n", (x))
#define gtl(x) getline(cin, (x))
#define flsh fflush(stdout)
#define sws ios::sync_with_stdio(false); cin.tie(0)
#define gcd __gcd
#define clr(x) memset(x,0,sizeof(x))
#define all(a) (a).begin(), (a).end()
#define foreach(i,a) for(__typeof((a).begin()) i = (a).begin(); i != (a).end(); ++i)
#define sz(a) (int)((a).size())

/*ll gcd(ll a, ll b)
{
	if(b == 0)
		return a;
	return gcd(b, a%b);
}*/

ll modx(ll Base, ll exponent)
{
	ll ans = 1;
	if(Base == 1)
		return Base;
	while(exponent)
	{
		if(exponent & 1)
			ans = (ans * Base)%mod;
		Base = (Base * Base)%mod;
		exponent = exponent >> 1;
	}
	return ans;
}

ll inmodx(ll num)
{
	return (modx(num, mod-2LL));
}

struct node
{
	node()
	{
		
	}
};

bool cmp()
{
	return false;
}

const int N = 100009;

int a[N];

int main()
{
	// freopen("D:/Coding Problems/Contest/input_file.in", "r", stdin);
	// freopen("D:/Coding Problems/Contest/output_file.out", "w", stdout);
	sws;
	int n, i, ans = 0, j, x;
	cin >> n;
	fo(i,1,n+1)
		cin >> a[i];
	fo(i,1,100)
	{
		x = 0;
		fo(j,1,n+1)
		{
			if(a[j] == i || a[j] == i+1)
				x++;
		}
		ans = max(ans, x);
	}
	cout << ans;
	return 0;
}