using System;

using System.Net;

public class Program

{

    public static void Main()

    {

        string ipAddressString = "173.160.21.227"; // Example IPv6 address

        string subnetMaskCIDR = "/30";

​

        string networkAddress = GetNetworkAddress(ipAddressString, subnetMaskCIDR);

​

        if (networkAddress != null)

        {

            Console.WriteLine($"IP Address: {ipAddressString}");

            Console.WriteLine($"Subnet Mask (CIDR): {subnetMaskCIDR}");

            Console.WriteLine($"Network Address: {networkAddress}");

        }

        else

        {

            Console.WriteLine("Invalid IP address format.");

        }

    }

    static string GetNetworkAddress(string ipAddressString, string subnetMaskCIDR)

    {

        try

        {

            IPAddress ipAddress = IPAddress.Parse(ipAddressString);

​

            // Parse CIDR notation to get prefix length

            int prefixLength = int.Parse(subnetMaskCIDR.Substring(1));

​

            // Calculate subnet mask based on prefix length

            byte[] subnetMaskBytes = ipAddress.GetAddressBytes();

​

            for (int i = prefixLength; i < subnetMaskBytes.Length * 8; i++)

            {

                int byteIndex = i / 8;

                int bitOffset = i % 8;

                subnetMaskBytes[byteIndex] &= (byte)~(1 << (7 - bitOffset));

            }

​

            IPAddress subnetMask = new IPAddress(subnetMaskBytes);

​

            // Perform bitwise AND to get the network address

            byte[] ipAddressBytes = ipAddress.GetAddressBytes();

            byte[] networkBytes = new byte[ipAddressBytes.Length];

​

            for (int i = 0; i < ipAddressBytes.Length; i++)

            {

                networkBytes[i] = (byte)(ipAddressBytes[i] & subnetMaskBytes[i]);

            }

​

            IPAddress networkAddress = new IPAddress(networkBytes);

            return networkAddress.ToString();

        }

        catch (FormatException)

        {

            return null; // Invalid IP address format

        }

    }

}