var i, imgs, pic, n, timer;
function prev() {(i<1) ? i=(n-1):i=i-1;
pic.src = imgs[i];} 
function next() { i=(i+1)%n;
pic.src = imgs[i];} 
function play() {i=(i+1)%n;
pic.src = imgs[i];
timeron=setTimeout(play,5000);}
function init(){pic = document.getElementById("gr"); 
imgs = [ "mhbrookie.jpg", "bugsampling.jpg", "elbrown.jpg", "shocking.jpg"];
n=imgs.length;
var preload= new Array(); for( i=0; i< n; i++ )
{ preload[ i ] = new Image(); preload[ i ].src = imgs[ i ];} 
i=-1; play();} onload=init;