var prefix = "block";

function showOnly(nr)
{
	//alert("showOnly"+nr);
	i = 0;
	var el = document.getElementById(prefix+i);
	while (el != null)
	{
		if (i!=nr)
			el.style.display = "none";
		else
			el.style.display = "block";
		i++;
		el = document.getElementById(prefix+i);
	}
}