#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(ll i=0;i<n;i++)
#define repp(i,a,b) for(ll i=a;i<=b;i++)
#define reff(i,a,b) for(ll i=a;i>=b;i--)
#define ll long long int
#define pll pair<ll,ll>
#define mb make_pair
#define pb push_back
#define F first
#define S second
#define M 1000000007
int main()
{
  ll n;
  cin>>n;
  ll a[n];
  rep(i,n)
  cin>>a[i];
  ll ans=1,tm=1;
  sort(a,a+n);
  ll p=a[0];
  repp(i,1,n-1)
  {
  	 if(a[i]-p<=1)
  	 {
  	  tm++;
  	  ans=max(ans,tm);
     }
     else
     {
       tm=1;
       p=a[i];
      }
  }
  cout<<ans;
}