function area_over_a(index)
{
	for (var i = 1; i <= 2; i++)
	{
		if (document.getelementbyid("tcontenta" + i.tostring()) != null)
		{
			document.getelementbyid("tcontenta" + i.tostring()).style.display = 'none';
		}
	}
	document.getelementbyid("tcontenta" + index.tostring()).style.display = 'block';
}