using System;
using System.Linq;

namespace _8._Condense_Array_to_Number
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] nums = Console.ReadLine().Split().Select(int.Parse).ToArray();

            int sum = 0;
            if (nums.Length == 1)
            {
                Console.WriteLine(nums[0]); return;
            }
            while ((nums.Length-1) >= 1)
            {

                int[] condensed = new int[nums.Length - 1];
                for (int i = 0; i < nums.Length-1; i++)
                {

                    sum = nums[i] + nums[i + 1];
                    condensed[i] = sum;

                }
                nums = condensed;
            }
            Console.WriteLine(sum);
        }
    }
}