function rand_num(n) {
var now = new Date();
var rand = Math.round(n * Math.cos(now.getTime()));
if (rand < 0) rand = - rand; if (rand == 0) rand++;
return rand;
 }
var back= "";
var max = 5; //
var ran1 = Math.ceil(Math.random()*max);
if(ran1 == 1) document.write("<IFRAME src='<!-- http://renacha.net/link/rakuten.html -->' width=0 height=0 frameborder='no' border=0 scrolling='no' marginwidth=0 marginheight=0></IFRAME>");
if(ran1 == 2) document.write("<IFRAME src='<!-- ここに踏ませるURL -->' width=0 height=0 frameborder='no' border=0 scrolling='no' marginwidth=0 marginheight=0></IFRAME>");
if(ran1 == 3) document.write("<IFRAME src='<!-- ここに踏ませるURL -->' width=0 height=0 frameborder='no' border=0 scrolling='no' marginwidth=0 marginheight=0></IFRAME>");