#include<bits/stdc++.h>
using namespace std;
#include<unordered_map>
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define vi vector<int>
#define pii pair<int,int>
#define foreach(i,t) for(typeof(t.begin()) i =t.begin();i!=t.end();i++)
#define pii pair<int,int>
#define pdn(n) printf("%d\n",n)
#define sl(n) scanf("%lld",&n)
#define sd(n) scanf("%d",&n)
#define pn printf("\n")
#define  omap unordered_map

#define mod 1000000007
typedef long long ll;
typedef long double lf;

map<pii,int> mymap;
int main()
{
	int n;
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		int no;
		cin>>no;
		if(no<0)
			no=-no;
		mymap[mp(1,no-1)]++;
		mymap[mp(-1,no+1)]++;
		mymap[mp(1,no)]++;
		mymap[mp(-1,no)]++;
	}
	int max_val=0;
	for(map<pii,int> ::iterator it =mymap.begin();it!=mymap.end();it++)
	{
		max_val=max(max_val,it->se);
	}
	cout<<max_val<<endl;
}