using System;

public class Program

{

    public static void Main()

    {

        var array = new []{-1, 3, -4, 5, 1, -6, 2, 1};

        PrintAllEquilibrium(array);

    }

    public static void PrintAllEquilibrium(int[] array)

    {   

        var rightSum = 0;

​

        for(var index = 0; index < array.Length; ++index)

        {

            rightSum += array[index];

        }

​

        var leftSum = 0;

​

        var foundAtleastOne = false;

        for(var index = 0; index < array.Length; ++index)

        {

            if(index > 0)

            {

                leftSum += array[index - 1];

            }

​

            rightSum -= array[index];

​

            if(leftSum == rightSum)

            {

                foundAtleastOne = true;

                Console.WriteLine(index);

            }

        }

​

        if (!foundAtleastOne)

        {

            Console.WriteLine(-1);

        }

    }

}