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.01 Ch.006","v01/c006"],
  ["Vol.02 Ch.007","v02/c007"],
  ["Vol.02 Ch.008","v02/c008"],
  ["Vol.02 Ch.009","v02/c009"],
  ["Vol.02 Ch.010","v02/c010"],
  ["Vol.02 Ch.011","v02/c011"],
  ["Vol.02 Ch.012","v02/c012"],
  ["Vol.03 Ch.013","v03/c013"],
  ["Vol.03 Ch.014","v03/c014"],
  ["Vol.03 Ch.015","v03/c015"],
  ["Vol.03 Ch.016","v03/c016"],
  ["Vol.03 Ch.017","v03/c017"],
  ["Vol.03 Ch.018","v03/c018"],
  ["Vol.04 Ch.019","v04/c019"],
  ["Vol.04 Ch.020","v04/c020"],
  ["Vol.04 Ch.021","v04/c021"],
  ["Vol.04 Ch.022","v04/c022"],
  ["Vol.04 Ch.023","v04/c023"],
  ["Vol.04 Ch.024","v04/c024"],
  ["Vol.05 Ch.025","v05/c025"],
  ["Vol.05 Ch.026","v05/c026"],
  ["Vol.05 Ch.027","v05/c027"],
  ["Vol.05 Ch.028","v05/c028"],
  ["Vol.05 Ch.029","v05/c029"],
  ["Vol.05 Ch.030","v05/c030"],
  ["Vol.06 Ch.031","v06/c031"],
  ["Vol.06 Ch.032","v06/c032"],
  ["Vol.06 Ch.033","v06/c033"],
  ["Vol.06 Ch.034","v06/c034"],
  ["Vol.06 Ch.035","v06/c035"],
  ["Vol.06 Ch.036","v06/c036"],
  ["Vol.07 Ch.037","v07/c037"],
  ["Vol.07 Ch.038","v07/c038"],
  ["Vol.07 Ch.039","v07/c039"],
  ["Vol.07 Ch.040","v07/c040"],
  ["Vol.07 Ch.041","v07/c041"],
  ["Vol.07 Ch.042","v07/c042"],
  ["Vol.08 Ch.043","v08/c043"],
  ["Vol.08 Ch.044","v08/c044"],
  ["Vol.08 Ch.045","v08/c045"],
  ["Vol.08 Ch.046","v08/c046"],
  ["Vol.08 Ch.047","v08/c047"],
  ["Vol.08 Ch.048","v08/c048"],
  ["Vol.09 Ch.049","v09/c049"],
  ["Vol.09 Ch.050","v09/c050"],
  ["Vol.09 Ch.051","v09/c051"],
  ["Vol.09 Ch.052","v09/c052"],
  ["Vol.09 Ch.053","v09/c053"],
  ["Vol.09 Ch.054","v09/c054"],
  ["Vol.10 Ch.000: 55-60","v10/c000"]
);

var total_chapters = 55;

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;