var chapter_list = new Array(
  ["Vol.01 Ch.001: Silver shadow","v01/c001"],
  ["Vol.01 Ch.002: Thin","v01/c002"],
  ["Vol.01 Ch.003: Aging","v01/c003"],
  ["Vol.01 Ch.004.1: invasion","v01/c004.1"],
  ["Vol.01 Ch.004.2","v01/c004.2"],
  ["Vol.02 Ch.005: Phantom Killer","v02/c005"],
  ["Vol.02 Ch.006: Nanaya","v02/c006"],
  ["Vol.02 Ch.007: Black","v02/c007"],
  ["Vol.02 Ch.008: Reprimand","v02/c008"],
  ["Vol.03 Ch.009.1: Resolve","v03/c009.1"],
  ["Vol.03 Ch.009.2","v03/c009.2"],
  ["Vol.03 Ch.010.1: Black King, White King","v03/c010.1"],
  ["Vol.03 Ch.010.2","v03/c010.2"],
  ["Vol.03 Ch.011.1: Foreboding","v03/c011.1"],
  ["Vol.03 Ch.011.2","v03/c011.2"],
  ["Vol.03 Ch.012: Descent","v03/c012"],
  ["Vol.03 Ch.013: Back","v03/c013"],
  ["Vol.04 Ch.014: Spring Snow","v04/c014"],
  ["Vol.04 Ch.015: Hiryu","v04/c015"],
  ["Vol.04 Ch.016: Helper","v04/c016"],
  ["Vol.04 Ch.017: Rei","v04/c017"],
  ["Vol.04 Ch.018: Kou","v04/c018"],
  ["Vol.04 Ch.019: Tear","v04/c019"],
  ["Vol.05 Ch.020","v05/c020"],
  ["Vol.05 Ch.021","v05/c021"],
  ["Vol.05 Ch.022","v05/c022"],
  ["Vol.05 Ch.023","v05/c023"],
  ["Vol.05 Ch.024","v05/c024"],
  ["Vol.05 Ch.025","v05/c025"],
  ["Vol.06 Ch.026","v06/c026"],
  ["Vol.06 Ch.027","v06/c027"],
  ["Vol.06 Ch.028","v06/c028"],
  ["Vol.06 Ch.029","v06/c029"],
  ["Vol.06 Ch.030","v06/c030"],
  ["Vol.06 Ch.031: Serpent","v06/c031"],
  ["Vol.06 Ch.032","v06/c032"],
  ["Vol.07 Ch.033","v07/c033"],
  ["Vol.07 Ch.034","v07/c034"],
  ["Vol.07 Ch.035","v07/c035"],
  ["Vol.07 Ch.036.1","v07/c036.1"]
);

var total_chapters = 40;

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;