Interface referance variable, C#

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//Title of this code
//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
   interface IA
    {
        
       
        
          void A_InterFace1();
          
        
       void A_InterFace2();   
        
    }
    
    class B:IA
    {
      public B()
        {
        }
        
        public  void A_InterFace1()
        {
            Console.WriteLine("Implement Interface1 in B");
        }
         public  void A_InterFace2()
        {
            Console.WriteLine("Implement Interface2 in B");
        }
    }
   class C:IA
    {
      public C()
        {
        }
        
        public  void A_InterFace1()
        {
            Console.WriteLine("Implement Interface1 in C");
        }
         public  void A_InterFace2()
        {
            Console.WriteLine("Implement Interface2 in C");
        }
    }
   
    public class Program
    {
        public static void Main(string[] args)
        {
            
           IA b=new B();
           IA c=new C();
            b.A_InterFace1();
            c.A_InterFace1();
        }
    }
}

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Compilation time: 0.06 sec, absolute running time: 0.06 sec, cpu time: 0.06 sec, average memory usage: 16 Mb, average nr of threads: 4