How to split large PDF document into multiple different ranges.

//Sets the different ranges to split the PDF document.
int[] SplitArray = new int[] { 3, 5, 4 };
 
//Loads the doucment.
PdfLoadedDocument ldoc = new PdfLoadedDocument("input.pdf");
int startIndex = 0;
int endIndex= 0;
for (int i = 0; i < SplitArray.Length; i++)
{
endIndex += SplitArray[i];
 
//Creates a new PDF document
PdfDocument doc = new PdfDocument();
 
// Import the pages to the new PDF document.
doc.ImportPageRange(ldoc, startIndex, endIndex-1);
 
startIndex = endIndex;
 
//Save the document.
doc.Save(i.ToString() + ".pdf" );
 
//Close the document.
doc.Close(true);
}
ldoc.Close(true);