randomImage(['main_01.jpg','main_02.jpg','main_03.jpg','main_04.jpg','main_05.jpg']);
	function randomImage(imgArr)
	{
		var imgSrc, imgW, imgH, r;
    		r = randomNumber(imgArr.length);
      		imgSrc = imgArr[r];
  		document.write('<IMG SRC=images/'+imgSrc+'>');
  	}