C#

using System;
using System.Collections.Generic;

namespace CalPoints {
    class Solution {
        public int CalPoints(string[] ops) {
           var opsList = new List<string>();
            var value = 0;

            foreach (var item in ops) {

                if (item.Equals("+")) {

                    var index = int.Parse(opsList[opsList.Count - 1]) + int.Parse(opsList[opsList.Count - 2]);
                    opsList.Add(index.ToString());

                    value = 0;

                    foreach (var val in opsList) {
                        value += int.Parse(val);
                    }

                } else if (item.Equals("D")) {

                    var index = int.Parse(opsList[opsList.Count - 1]) * 2;
                    opsList.Add(index.ToString());

                    value = 0;

                    foreach (var val in opsList) {
                        value += int.Parse(val);
                    }

                } else if (item.Equals("C")) {

                    opsList.RemoveAt(opsList.Count - 1);

                    value = 0;

                    foreach (var val in opsList) {
                        value += int.Parse(val);
                    }

                } else {
                    //An integer was added
                    opsList.Add(item);

                    foreach (var val in opsList) {
                        value += int.Parse(val);
                    }
                }

            }

            return value;
        }
    }

    class CalPoints {
        public static void Main(string[] args) {
            var solution = new Solution();
            var space = new char[] { ' ' };

            string[] ops = Console.ReadLine().Split(space);
            int output = solution.CalPoints(ops);
            Console.Write(output.ToString());
        }
    }

}

private void PdfReport(string address)
        {
            //Load the stream from the local system.

            PdfSource = new FileStream(address, FileMode.Open);
        }

class AsyncResponse
    {
        public AsyncResponse()
        {
            test2();
            Console.ReadKey();
        }

        public void test2()
        {
      
            for (int i = 0; i < 100; i++)
            {
                string url = "https//www.google.com";
   
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
                request.BeginGetResponse(new AsyncCallback(FinishWebRequest), request);
            }
            
        }

        private void FinishWebRequest(IAsyncResult result)
        {       
                HttpWebResponse response = (result.AsyncState as HttpWebRequest).EndGetResponse(result) as HttpWebResponse;

                Console.WriteLine("Finished");
        }

}

// Create a message
public class LoggedInUserRequestMessage : RequestMessage<User>
{
}

// Register the receiver in a module
WeakReferenceMessenger.Default.Register<MyViewModel, LoggedInUserRequestMessage>(this, (r, m) =>
{
    // Assume that "CurrentUser" is a private member in our viewmodel.
    // As before, we're accessing it through the recipient passed as
    // input to the handler, to avoid capturing "this" in the delegate.
    m.Reply(r.CurrentUser);
});

// Request the value from another module
User user = WeakReferenceMessenger.Default.Send<LoggedInUserRequestMessage>();