using System;

using System.Linq;          

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        var input = "d4 d3 52 ba 00 3e 80 c8 00 06 3a 45 cb 83 3b bc 6f e7 bd 61 3a 36 db 71 a6 5f a9 ea 49 a1 5b d6 67 85 e9 c3 c1 3e ca 74 72 fe da a8 88 c0 80 00 01 5d cb 43 6a 07 5a 98 9e 8a cb ec";

        //var input = "3a 8c 52 ba d4 d3 00 86 81 c8 00 0c 28 7d 14 e0 68 fd a9 3a f0 a2 22 8d 2c a1 40 34 67 b0 6e 65 a3 74 e1 4c eb bd 53 94 63 5a 80 4e 18 d9 28 db 10 91 5d c6 18 4a 01 e7 82 a4 bc 24 f6 6a 8d f4 88 82 c7 bc fd 16 a6 dc 95 8a 27 a0 ca 39 10 54 99 8f 22 a4 6e 65 52 74 f5 4b b9 d8 42 ae 61 9d 9a b1 ab fc 17 de cc 15 5a 11 80 6f 78 71 b4 d1 37 76 8b eb 5c dc bc 7c 80 00 03 5f e0 93 fc 31 b5 04 9f 48 fa 81";

        var hexNumbers = input.Split(' ');

        var numbers = new List<int>();

        Func<string, string> toBinary = (i) => Convert.ToString(Convert.ToInt64(i, 16), 2).PadLeft(8, '0');

        for(int i = 0; i < hexNumbers.Count(); i += 2)

        {

            var number = Convert.ToInt32(toBinary(hexNumbers[i]) + toBinary(hexNumbers[i+1]), 2);

            numbers.Add(number);

            Console.WriteLine(hexNumbers[i] + " (" + toBinary(hexNumbers[i]) + ") + " + hexNumbers[i+1] + " (" + toBinary(hexNumbers[i+1]) + ") = " + number.ToString().PadRight(5, ' ') + " (" + toBinary(hexNumbers[i])+ " " + toBinary(hexNumbers[i+1]) + ")");

        }   

        var sumBinary = Convert.ToString(numbers.Sum(), 2);

        Console.WriteLine("\nInt full sum:");

        Console.WriteLine(numbers.Sum());

        Console.WriteLine("Binary full sum:");

        Console.WriteLine(sumBinary);

        var cut = sumBinary[^16..];

        Console.WriteLine("\nInt cutted sum:");

        Console.WriteLine(Convert.ToInt32(cut, 2));

        Console.WriteLine("Binary cutted sum:");

        Console.WriteLine(cut);

        Console.WriteLine("Checksum:");

        var reversed = ~Convert.ToInt32(cut, 2);

        Console.WriteLine(Convert.ToString(reversed, 2)[^16..]);

    }

}

​