//Picking Numbers
//https://www.hackerrank.com/contests/101hack44/challenges/picking-numbers
#include <iostream>
#include <algorithm>
using namespace std;

int n,a[105],sum,maxi=0;
int main()
{
    cin>>n;
    for(int i=0;i<n;i++)
        cin>>a[i];
    sort(a,a+n);
    for(int i=0;i<n;i++)
    {
        sum=0;
        for(int j=i;j<n;j++)
        {
            if(a[j]-a[i]<=1)
                sum++;
            else break;
        }
        if(sum>maxi)
            maxi=sum;
    }
    cout<<maxi;
    return 0;
}