//By Rk4371
#include<bits/stdc++.h>
typedef long long int ll;
using namespace std;
bool isprime(ll n)
{
    // Corner cases
    if (n <= 1)  return false;
    if (n <= 3)  return true;

    // This is checked so that we can skip
    // middle five numbers in below loop
    if (n%2 == 0 || n%3 == 0) return false;

    for (ll i=5; i*i<=n; i=i+6)
        if (n%i == 0 || n%(i+2) == 0)
           return false;

    return true;
}
ll gcd(ll a,ll b)
{
   return((a == 0)? b:gcd(b%a, a));
}
ll diff(ll a,ll b)
{
	return((a>b)?(a-b):(b-a));
}
int main()
{
    ll n;
    cin>>n;
    ll a[n];
    for(ll i=0;i<n;i++)
        {
        cin>>a[i];
    }
    sort(a,a+n);
    ll maxc=0;
    for(ll i=0;i<n;i++)
        {
        ll tc=1;
            for(ll j=i+1;j<n;j++)
                {
                if(diff(a[i],a[j])<=1)
                    {
                    tc++;
                }
                else
                    {
                    break;
                }
            }
        if(tc>maxc)
            maxc=tc;
    }
    cout<<maxc;
return 0;
}