img = new Array();
img[0] = "img/main_img/main02_a.jpg";
img[1] = "img/main_img/main02_b.jpg";
img[2] = "img/main_img/main02_c.jpg";
img[3] = "img/main_img/main02_d.jpg";
img[4] = "img/main_img/main02_e.jpg";
img[5] = "img/main_img/main02_f.jpg";
img[6] = "img/main_img/main02_g.jpg";
img[7] = "img/main_img/main02_h.jpg";
img[8] = "img/main_img/main02_i.jpg";
img[9] = "img/main_img/main02_j.jpg";
img[10] = "img/main_img/main02_k.jpg";
img[11] = "img/main_img/main02_l.jpg";
img[12] = "img/main_img/main02_n.jpg";
n = Math.floor(Math.random()*img.length);
document.write("<img src='"+img[n]+"' border='0'>");