function over(n,k){
		  document.getElementById('li-'+k).style.background='url(images/nav-hover.jpg) no-repeat';
		  document.getElementById('a-'+k).style.color='#333';
		  document.getElementById('ul-'+k).style.display='block';
		  for(j=1;j<=n;j++){
			  if(j==k) continue;
		      document.getElementById('li-'+j).style.background='';
		      document.getElementById('a-'+j).style.color='#fff';
			  document.getElementById('ul-'+j).style.display='none';
			  }
		  }