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public static int? FindBalanceElement(int[]? array)
        {
            var sum = 0;

            for (int i = 1; i < array.Length;)
            {
                sum += i;
            }

               int i = 1,
               left = 0,
               right = sum - array[0];

            left = array[0];
            right = sum;
            i = 1;
            while (left < right)
            {
                left += array[i];
                right -= array[i];
                i++;
            }

            if (array.Length == 0)
            {
                throw new ArgumentException();
            }

            if (array is null)
            {
                throw new ArgumentNullException();
            }

            if (left == right)
            {
                return i;
            }
            else
            {
                return null;
            }
        }