Exam July Evening 5. Change Even Bits

using System;

public class ChangeEvenBits
{
    public static void Main()
    {
        checked
        {
            int count = int.Parse(Console.ReadLine());

            int[] nums = new int[count];
            for (int i = 0; i < nums.Length; i++)
            {
                nums[i] = int.Parse(Console.ReadLine());
            }

            ulong modifyingNum = ulong.Parse(Console.ReadLine());

            int countModifyedBits = 0;
            for (int i = 0; i < nums.Length; i++)
            {
                string binaryNum = Convert.ToString(nums[i], 2);
                int countBits = binaryNum.Length;
                int maxEvenBit = (countBits - 1) * 2;
                for (int bit = 0; bit <= maxEvenBit; bit += 2)
                {
                    int bitValue = (int)(modifyingNum & (ulong)(1 << bit));
                    if (bitValue == 0)
                    {
                        countModifyedBits++;
                        modifyingNum |= (ulong)1 << bit;
                    }
                }
            }

            Console.WriteLine(modifyingNum);
            Console.WriteLine(countModifyedBits);
        }
    }
}