#include<bits/stdc++.h>
using namespace std;
#define sd(x) scanf("%d",&x)
#define slld(x) scanf("%lld",&x)
#define ss(x) scanf("%s",x)
#define mod 1000000007
#define bitcount __builtin_popcountll
#define ll long long
#define pb push_back
#define pi pair<int,int>
#define pii pair<pi,int>
#define mp make_pair
int main()
{
	int i,j,k;
	int n,arr[105];
	sd(n);
	for(i=0;i<n;i++)
		sd(arr[i]);
	sort(arr,arr+n);
	int ans=0;
	for(i=0;i<n;i++)
	{
		j=i+1;
		while(j<n&&arr[j]-arr[i]<=1)
			j++;
		ans=max(ans,j-i);
	}
	printf("%d\n",ans );
	return 0;
}