Extract some pages and save that file

I am writing a function that extracts some pages from a document so it can be used as proof. I have used a switch case that if it is true will output some pages. In the third case I want to extract the first two pages of the document, the 23rd and 24th and the two last pages. This is what I cant solve. Can I just use the this.extractPages method or do I have to use the insertPages method also. If I need the insertPages method how do I use it. The code is inside a trusted function.

  switch (true){

  case this.numPages == 1:

  this.extractPages(0,0, newPath);

  app.alert("A one paged proof has been created",3)

  break;

  case ( (this.numPages > 1) && (this.numPages < 9) 😞

  this.extractPages(0,1, newPath);

  app.alert("A two paged proof has been created",3)

  break;

(PROBLEM IS HERE) 

  case ( (this.numPages > 9) && (this.numPages < 49) 😞

  this.extractPages(0,1, newPath);

  app.alert("A proof has been created",3)

  break;

  default:

  app.alert("No proof has been created",3)

  break;