C#.Net Async and await Attribute used (C# 5)

//Async / await, caller information attributes

using System;
using System.IO;
using System.Threading.Tasks;

class Program
{
    static void Main()
    {
// Create task and start it.
// ... Wait for it to complete.
Task task = new Task(ProcessDataAsync);
task.Start();
task.Wait();
Console.ReadLine();
    }

    static async void ProcessDataAsync()
    {
// Start the HandleFile method.
Task<int> task = HandleFileAsync("C:\\1.txt");

// Control returns here before HandleFileAsync returns.
// ... Prompt the user.
Console.WriteLine("Please wait patiently " +
   "while I do something important.");

// Wait for the HandleFile task to complete.
// ... Display its results.
int x = await task;
Console.WriteLine("Count: " + x);
    }

    static async Task<int> HandleFileAsync(string file)
    {
Console.WriteLine("HandleFile Enter");
int count = 0;

// Read in the specified file.
// ... Use async StreamReader method.
using (StreamReader reader = new StreamReader(file))
{
   string v = await reader.ReadToEndAsync();

   // ... Process the file data somehow.
   count += v.Length;

   // ... A slow-running computation.
   //     Dummy code.
   for (int i = 0; i < 10000; i++)
   {
int x = v.GetHashCode();
if (x == 0)
{
   count--;
}
   }
}
Console.WriteLine("HandleFile Exit");
return count;
    }
}

Output: initial

HandleFile Enter
Please wait patiently while I do something important.

Output: final

HandleFile Enter
Please wait patiently while I do something important.
HandleFile Exit

Count: 1916146