09. Jump Around

using System;
using System.Linq;

namespace _09.Jump_Around
{
    class Program
    {
        static void Main(string[] args)
        {
            var numbers = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();

            var sum = numbers[0];
            var step = numbers[0];
            var index = Array.IndexOf(numbers, step);


            while (true)
            {
                try
                {
                    index = Array.IndexOf(numbers, numbers[index + step]);
                    step = numbers[index];
                    sum += step;
                }
                catch (Exception e)
                {
                    try
                    {
                        index = Array.IndexOf(numbers, numbers[index - step]);
                        step = numbers[index];
                        sum += step;
                    }
                    catch (Exception ex)
                    {
                        Console.WriteLine(sum);
                        return;
                    }
                }
            }
        }
    }
}