App config file in CSharp

using System;
using System.Collections.Generic;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {

            Console.WriteLine(System.Configuration.ConfigurationManager.AppSettings["username"]);
            Console.WriteLine(System.Configuration.ConfigurationManager.AppSettings["password"]);
        }
    }
}

App.config file:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <appSettings>
    <add key="username" value="wxf"/>
    <add key="password" value="fxw"/>
  </appSettings>
</configuration>

Output results:
wxf
fxw