var imgMax  = 5; //セットする画像の枚数。
var imgRand = Math.floor(Math.random() * imgMax);

if(imgRand == 0)        document.write('<script type="text/javascript" src="cover_photo_AD01.js"></script>');
else if(imgRand == 1)   document.write('<script type="text/javascript" src="cover_photo_AD03.js"></script>');
else if(imgRand == 2)   document.write('<script type="text/javascript" src="cover_photo_AD05.js"></script>');
else if(imgRand == 3)   document.write('<script type="text/javascript" src="cover_photo_AD06.js"></script>');
else if(imgRand == 4)   document.write('<script type="text/javascript" src="cover_photo_AD12.js"></script>');