function tshow(i)
{
	document.getElementById("pg1").className='no';document.getElementById("pg2").className='no';
	document.getElementById("pg3").className='no';document.getElementById("pg4").className='no';
	document.getElementById("pg"+i).className='yes';
	document.getElementById("pgs1").style.display='none';document.getElementById("pgs2").style.display='none';
	document.getElementById("pgs3").style.display='none';document.getElementById("pgs4").style.display='none';
	document.getElementById("pgs"+i).style.display='';
}