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.001","v02/c001"],
  ["Vol.02 Ch.002","v02/c002"],
  ["Vol.02 Ch.003","v02/c003"],
  ["Vol.02 Ch.004","v02/c004"],
  ["Vol.02 Ch.005.1","v02/c005.1"],
  ["Vol.02 Ch.005.2","v02/c005.2"],
  ["Vol.02 Ch.006","v02/c006"],
  ["Vol.03 Ch.001","v03/c001"],
  ["Vol.03 Ch.002","v03/c002"],
  ["Vol.03 Ch.003","v03/c003"],
  ["Vol.03 Ch.004.1","v03/c004.1"],
  ["Vol.03 Ch.004.2","v03/c004.2"],
  ["Vol.03 Ch.005","v03/c005"],
  ["Vol.03 Ch.006","v03/c006"],
  ["Vol.03 Ch.007","v03/c007"],
  ["Vol.04 Ch.001","v04/c001"],
  ["Vol.04 Ch.002","v04/c002"],
  ["Vol.04 Ch.003","v04/c003"],
  ["Vol.04 Ch.004","v04/c004"],
  ["Vol.04 Ch.005","v04/c005"],
  ["Vol.04 Ch.006","v04/c006"],
  ["Vol.04 Ch.007","v04/c007"],
  ["Vol.05 Ch.001","v05/c001"],
  ["Vol.05 Ch.002","v05/c002"],
  ["Vol.05 Ch.003","v05/c003"],
  ["Vol.05 Ch.004","v05/c004"],
  ["Vol.05 Ch.005","v05/c005"],
  ["Vol.05 Ch.006","v05/c006"],
  ["Vol.05 Ch.007","v05/c007"],
  ["Vol.06 Ch.001","v06/c001"],
  ["Vol.06 Ch.002","v06/c002"],
  ["Vol.06 Ch.003","v06/c003"],
  ["Vol.06 Ch.004","v06/c004"],
  ["Vol.06 Ch.005","v06/c005"],
  ["Vol.06 Ch.006","v06/c006"],
  ["Vol.06 Ch.007","v06/c007"],
  ["Vol.07 Ch.000","v07/c000"],
  ["Vol.08 Ch.001","v08/c001"],
  ["Vol.08 Ch.002","v08/c002"],
  ["Vol.08 Ch.003","v08/c003"],
  ["Vol.08 Ch.004","v08/c004"],
  ["Vol.08 Ch.005","v08/c005"],
  ["Vol.08 Ch.006","v08/c006"],
  ["Vol.08 Ch.007","v08/c007"],
  ["Vol.09 Ch.001","v09/c001"],
  ["Vol.09 Ch.002","v09/c002"],
  ["Vol.09 Ch.003","v09/c003"],
  ["Vol.09 Ch.004","v09/c004"],
  ["Vol.09 Ch.005","v09/c005"],
  ["Vol.09 Ch.006","v09/c006"],
  ["Vol.09 Ch.007","v09/c007"],
  ["Vol.10 Ch.001","v10/c001"],
  ["Vol.10 Ch.002","v10/c002"],
  ["Vol.10 Ch.003","v10/c003"],
  ["Vol.10 Ch.004","v10/c004"],
  ["Vol.10 Ch.005","v10/c005"],
  ["Vol.10 Ch.006","v10/c006"],
  ["Vol.10 Ch.007","v10/c007"]
);

var total_chapters = 63;

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;