using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(sumList(Enumerable.Range(1,7).ToList()));

    }

    private static int sumArray(int[] nums)

    {

        if(nums.Length ==0)

            return 0;

        return nums[0] + sumArray(nums[1..]);

    }

    private static int sumList(List<int> nums)

    {

        if(nums.Count ==0)

            return 0;

        return nums[0] + sumList(nums.GetRange(1, nums.Count-1));

    }

}