/*********** [ scopeInfinity ] ******************/
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef std::vector<ll> vll;

#define endl '\n' 
#define mp make_pair
#define pb(x) push_back((x))

ll MOD = 1e9+7;
ll INF = LLONG_MAX;

vector<string> &split(const std::string &s, char delim, vector<string> &e) {
    stringstream ss(s);
    string item;
    while(getline(ss, item, delim))
        e.push_back(item);
    return e;
}


ll Pow(ll a ,int b ,int Mo){
    ll ans = 1;
    for (; b; b >>= 1, a = a * a % Mo)
        if (b&1) ans = ans * a % Mo;
    return ans;
}

long solve() {
	
	
	return 0;
}

int main(int argc, char const *argv[])
{
	std::ios::sync_with_stdio(false);
	// cout<<fixed<<setprecision(1);
	
	std::vector<ll> v(200,0);
	ll n;
	cin>>n;
	for (int i = 0; i < n; ++i)
	{
	ll x;
	cin>>x;
	v[x]++;
	}
	ll c=0;
	for (int i = 0; i < 199; ++i)
	{
		c=max(c,v[i]+v[i+1]);
	}
	cout<<c;


	return 0;
}