/* preload images */
if(document.images) {
 var imgs = new Array();
	imgs[9] = new Image();  imgs[9].src = "/e_tracks/hello_pc/common/img/navi_img/b_01.gif";
 	imgs[10] = new Image();  imgs[10].src =	"/e_tracks/hello_pc/common/img/navi_img/b_01_over.gif";
	imgs[11] = new Image();  imgs[11].src = "/e_tracks/hello_pc/common/img/navi_img/b_02.gif";
	imgs[12] = new Image();  imgs[12].src = "/e_tracks/hello_pc/common/img/navi_img/b_02_over.gif";
	imgs[13] = new Image();  imgs[13].src = "/e_tracks/hello_pc/common/img/navi_img/b_03.gif";
	imgs[14] = new Image();  imgs[14].src = "/e_tracks/hello_pc/common/img/navi_img/b_03_over.gif";
 	imgs[15] = new Image();  imgs[15].src =	"/e_tracks/hello_pc/common/img/navi_img/b_04.gif";
	imgs[16] = new Image();  imgs[16].src = "/e_tracks/hello_pc/common/img/navi_img/b_04_over.gif";
	imgs[17] = new Image();  imgs[17].src = "/e_tracks/hello_pc/common/img/navi_img/b_05.gif";
	imgs[18] = new Image();  imgs[18].src = "/e_tracks/hello_pc/common/img/navi_img/b_05_over.gif";
}

/* swap image */
function chgimg(id, imgname) {
 if(document.images) {
  if(imgs[imgname]) {
    document.images[id].src = imgs[imgname].src;
  }
  else {
    document.images[id].src = imgname;
  }
 }
}