using System;
using System.Linq;

namespace Problem11.EqualSums
{
    internal class Program
    {
        public static void Main(string[] args)
        {
            int[] numbers = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();

            int leftSum = 0;
            int rightSum = 0;
            bool isTrue = false;
            for (int i = 0; i < numbers.Length; i++)
            {
                for (int left = 0; left < i; i++)
                {
                    leftSum += numbers[left];
                }

                for (int right = i + 1; right < numbers.Length; right++)
                {
                    rightSum += numbers[right];
                }

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

                leftSum = 0;
                rightSum = 0;
            }

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