11

using System;
using System.Linq;

namespace ExamPreparation
{
    class Startup
    {
        static void Main()
        {
            int[] numbers = Console.ReadLine().Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries)
                .Select(int.Parse)
                .ToArray();

            if (numbers.Length == 0)
            {
                Console.WriteLine(numbers[0]);
            }
            else
            {
                bool found = false;

                for (int i = 0; i < numbers.Length; i++)
                {
                    int rightSum = 0;
                    int leftSum = 0;

                    for (int l = 0; l <= i; l++)
                    {
                        leftSum += numbers[l];
                    }

                    for (int r = numbers.Length - 1; r >= i; r--)
                    {
                        rightSum += numbers[r];
                    }

                    if (leftSum == rightSum)
                    {
                        Console.WriteLine(i);
                        found = true;
                        break;
                    }
                }

                if (!found)
                {
                    Console.WriteLine("no");
                }
            }
        }
    }
}