var theImages = new Array()

theImages[0] = '01.png'

theImages[1] = '02.png'

theImages[2] = '03.png'

theImages[3] = '04.png'

theImages[4] = '05.png'

theImages[5] = '06.png'

theImages[6] = '07.png'

theImages[7] = '08.png'

theImages[8] = '09.png'

theImages[9] = '10.gif'

theImages[10] = '11.png'

theImages[11] = '12.gif'

var j = 0

var p = theImages.length;

var preBuffer = new Array()

for (i = 0; i < p; i++){

   preBuffer[i] = new Image()

   preBuffer[i].src = theImages[i]

}

var whichImage = Math.round(Math.random()*(p-1));

function showImage(){

document.write('<img class="imgcentro" src="../imagenes/imgaleatorias/'+theImages[whichImage]+'" height="110" width="400" alt="" />');

}