var	prev=-1;
function Flip(n) {
	var	s=document.styleSheets[0];
	var theRules=new Array();
	if(s.cssRules)
		theRules=s.cssRules;
	else
		if(s.rules)
			theRules=s.rules;
	if(prev!=-1) {
		theRules[prev].style.color='black';
		theRules[prev+10].style.display='none';
	}
	theRules[n].style.color='red';
	theRules[n+10].style.display='';
	prev=n;
}