var char = new Array();
char[0] = String.fromCharCode(97 + Math.round(Math.random() * 25));
for (i=0;i<char.length;i++)
{
document.write('<a href="http://www.difmatamoros.gob.mx/albums/dif-albums/ad'+char[i]+'.jpg" rel="lightbox[principal]"><img src="http://www.difmatamoros.gob.mx/albums/dif-albums/ad'+char[i]+'.thumb.jpg" width="75" height="75" class="sinmarco" /></a>');
}