meine Frage wird in diesem Code angezeigt

Ich habe Klasse so

public class  maincs
{
  public int a;
  public int b;
  public int c;
  public int d; 
}

public class  sub1
{
  public int a;
  public int b;
  public int c;
}


public void methoda (sub1 model)
{
  maincs mdata = new maincs(){a = model.a , b = model.b , c= model.c} ;   

  // is there is a way to directly cast class sub1 into main like that    
  mdata = (maincs) model;    
}