Code:
<script>
var pic=new Array("","IMGP0274.JPG","IMGP0275.JPG","IMGP0276.JPG","IMGP0277.JPG");
var i=0;
function gox(){
	document.room.src=pic[i];
	document.getElementById('ses').value=i;
	i++;
	if(i==5) i=0;
}
</script>

<form>
	<img src="" name="room"><p></p>
	<input type="button" value="here we go" onclick="gox();">
	<input type="button" value="" id="ses">
</form>
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