if(document.images) {
 var img_d = new Array();
  img_d[10] = new Image();  img_d[10].src = "topgazo/bt01a.jpg";
  img_d[20] = new Image();  img_d[20].src = "topgazo/bt02a.jpg";
  img_d[30] = new Image();  img_d[30].src = "topgazo/bt03a.jpg";
  img_d[40] = new Image();  img_d[40].src = "topgazo/bt04a.jpg";
  img_d[50] = new Image();  img_d[50].src = "topgazo/bt05a.jpg";
  img_d[60] = new Image();  img_d[60].src = "topgazo/bt06a.jpg";
  img_d[70] = new Image();  img_d[70].src = "topgazo/bt07a.jpg";
  img_d[11] = new Image();  img_d[11].src = "topgazo/bt01b.jpg";
  img_d[21] = new Image();  img_d[21].src = "topgazo/bt02b.jpg";
  img_d[31] = new Image();  img_d[31].src = "topgazo/bt03b.jpg";
  img_d[41] = new Image();  img_d[41].src = "topgazo/bt04b.jpg";
  img_d[51] = new Image();  img_d[51].src = "topgazo/bt05b.jpg";
  img_d[61] = new Image();  img_d[61].src = "topgazo/bt06b.jpg";
  img_d[71] = new Image();  img_d[71].src = "topgazo/bt07b.jpg";

}

function kawaru(id, imgname) {
 if(document.images) {
  if(img_d[imgname]) {
    document.images[id].src = img_d[imgname].src;
  }
  else {
    document.images[id].src = imgname;
  }
 }
}