function showcontent(n, s)
	{
    for(i=1;i<s;i++)
    {
     eval("document.getElementById('nav"+i+"').className=''");
    }
    eval("document.getElementById('nav"+n+"').className='on'");
    
    for(i=1;i<s;i++)
    {
      eval("document.getElementById('c"+i+"').style.display='none'")
    }
      eval("document.getElementById('c"+n+"').style.display='block'");
   }