using System;
using System.Linq;

namespace Condense_Array_to_Number
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] numbers = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
            int sum = 0;
            int firstLength = numbers.Length - 1;

            for (int i = 0; i < firstLength; i++)
            {
                int[] condenced = new int[numbers.Length - 1];
                for (int j = 0; j < condenced.Length; j++)
                {
                    condenced[j] = numbers[j] + numbers[j + 1];
                }
                numbers = condenced;
                sum = condenced[0];
            }

            Console.WriteLine(sum);
        }
    }
}