if(document.images) {
pics = new Array(); 
pics[1] = new Image();
pics[1].src = "/images/bu_1_1.jpg"; 
pics[2] = new Image();
pics[2].src = "/images/bu_1_2.jpg";
pics[3] = new Image();
pics[3].src = "/images/bu_1_3.jpg";

pics[4] = new Image();
pics[4].src = "/images/bu_2_1.jpg"; 
pics[5] = new Image();
pics[5].src = "/images/bu_2_2.jpg";
pics[6] = new Image();
pics[6].src = "/images/bu_2_3.jpg";

pics[7] = new Image();
pics[7].src = "/images/bu_3_1.jpg"; 
pics[8] = new Image();
pics[8].src = "/images/bu_3_2.jpg";
pics[9] = new Image();
pics[9].src = "/images/bu_3_3.jpg";

pics[10] = new Image();
pics[10].src = "/images/bu_4_1.jpg"; 
pics[11] = new Image();
pics[11].src = "/images/bu_4_2.jpg";
pics[12] = new Image();
pics[12].src = "/images/bu_4_3.jpg";


}

function changer(from,to) {
if(document.images) {
document.images[from].src = pics[to].src;
}
}