using System;

using System.Collections.Generic;

using System.Net;

using System.Net.NetworkInformation;

using System.Threading.Tasks;

using System.Threading.Tasks.Dataflow;

using System.Text.RegularExpressions;

using System.Linq;

using System.Globalization;

​

public class Program

{

    private static List<IPStatus> _results;

    public static async Task MyMethodAsync(IPAddress ip)

    {

        await Task.Delay(500);

        Console.WriteLine("processing");

    }

​

    public static async Task Asd()

    {

        var options = new ExecutionDataflowBlockOptions{MaxDegreeOfParallelism = 2};

        var block = new ActionBlock<IPAddress>(ip => MyMethodAsync(ip), options);

        var list = new List<IPAddress>{IPAddress.Loopback, IPAddress.Loopback, IPAddress.Loopback, IPAddress.Loopback, IPAddress.Loopback, IPAddress.Loopback, IPAddress.Loopback, IPAddress.Loopback, IPAddress.Loopback};

        foreach (var ip in list)

        {

            block.Post(ip);

        }

​

        block.Complete();

        await block.Completion;

    }

​

    public static void Main()

    {

        var s = "hello world orl";                   //OUTPUT: ll orl or

        List<char> repeatedChars = new List<char>();

​

        List<char> tmp = new List<char>();

        for(int i = 0; i< s.Length - 1; i++)

        {

            if( s[i+1]== s[i])

            {

                repeatedChars.Add(s[i]);

                repeatedChars.Add(s[i+1]);

​

            }

        }

​

        for(int i = 0; i< s.Length - 1; i++)

        {

            if(s.Count(f=> f == s[i]) > 1)

            {

                int substringmatchsize= 1;

                while ( s.Count(f=>f= s.Substring(i,i+substringmatchsize)) >1)

                {

                }

                 tmp.Add(s[i]);

                 Console.Write(s[i]);

​

            }

        }

​

        Console.Write("\nOUTPUT\n");

        foreach(var t in tmp)

            Console.Write(t);

      }

}