#include<bits/stdc++.h>
#define ll long long
using namespace std;
int main()
{
	int n,a[105],freq[105]={0};
	cin>>n;
	for(int i=0;i<n;i++)
	{
		cin>>a[i];
		freq[a[i]]++;
	}
	sort(a,a+n);
	int cnt=0,ans=0;
	for(int i=0;i<n;i++)
	{
		cnt+=freq[a[i]-1]+freq[a[i]];
		ans=max(ans,cnt);
		cnt=0;
		cnt+=freq[a[i]+1]+freq[a[i]];
		ans=max(ans,cnt);
		cnt=0;
	}
	cout<<ans<<"\n";
	return 0;
}