using System;

public abstract class Product{
  public Product(){}
}

public class ConcreteProduct_1: Product{
  public ConcreteProduct_1(){}
}

public class ConcreteProduct_2: Product{
  public ConcreteProduct_2(){}
}


public abstract class Creator{
  public abstract Product FactoryMethod();

  public void SomeOperation(){
    Product product =  FactoryMethod();
  }
}

public class ConcreteCreator_1: Creator{
  public override Product FactoryMethod(){
    return new ConcreteProduct_1();
  }
}

public class ConcreteCreator_2: Creator{
  public override Product FactoryMethod(){
    return new ConcreteProduct_2();
  }
}