using System;

public class Program

{

    public static int maxloot =0;

    public void Sticker(int[] arr)

    {

        for(int i=0;i<arr.Length;i++)

        {

            FindHome(arr,i,arr[i]);

        }

    }

    public void FindHome(int[] arr ,int start,int sum)

    {

        if(sum>maxloot)

        {

            maxloot=sum;

        }

        if(start>=arr.Length)

        {

            return;

        }

        for(int i=start+2;i<arr.Length;i=i+2)

        {

            FindHome(arr,i,sum+arr[i]);

        }

    }

    public static void Main()

    {

        int[] arr=new int[]{4, 4, 4, 4};

        Program p =new Program();

        p.Sticker(arr);

        Console.WriteLine(maxloot);

    }

}