var chapter_list = new Array(
  ["Vol.01 Ch.001","v01/c001"],
  ["Vol.01 Ch.002","v01/c002"],
  ["Vol.01 Ch.003","v01/c003"],
  ["Vol.01 Ch.004","v01/c004"],
  ["Vol.01 Ch.005","v01/c005"],
  ["Vol.02 Ch.006","v02/c006"],
  ["Vol.02 Ch.007","v02/c007"],
  ["Vol.03 Ch.001","v03/c001"],
  ["Vol.03 Ch.002","v03/c002"],
  ["Vol.03 Ch.008","v03/c008"],
  ["Vol.03 Ch.009.1","v03/c009.1"],
  ["Vol.03 Ch.009.2","v03/c009.2"],
  ["Vol.04 Ch.001.1: Extra","v04/c001.1"],
  ["Vol.04 Ch.002","v04/c002"],
  ["Vol.04 Ch.003","v04/c003"],
  ["Vol.04 Ch.004","v04/c004"],
  ["Vol.04 Ch.004.2","v04/c004.2"],
  ["Vol.05 Ch.010.1","v05/c010.1"],
  ["Vol.05 Ch.010.2","v05/c010.2"],
  ["Vol.05 Ch.010.3","v05/c010.3"],
  ["Vol.05 Ch.010.4","v05/c010.4"],
  ["Vol.06 Ch.010.5","v06/c010.5"],
  ["Vol.06 Ch.011.1: Ivan The Fool","v06/c011.1"],
  ["Vol.06 Ch.011.2","v06/c011.2"],
  ["Vol.06 Ch.011.3","v06/c011.3"]
);

var total_chapters = 25;

for (var i = 0; i < chapter_list.length; i++) {
  document.getElementById('top_chapter_list').options[i] = new Option(chapter_list[i][0], chapter_list[i][1]);
  document.getElementById('bottom_chapter_list').options[i] = new Option(chapter_list[i][0], chapter_list[i][1]);
}
document.getElementById('top_chapter_list').value=current_chapter;
document.getElementById('bottom_chapter_list').value=current_chapter;
var current_chapter_index = document.getElementById('top_chapter_list').selectedIndex;