function getObj(name){
	if (document.getElementById){
	   return document.getElementById(name);
	}else if (document.all) {
	   return document.all[name];
	}else if (document.layers){
	   if (document.layers[name]){
	   		return document.layers[name];
	   }else{
	    	return document.layers.nsend.layers[name];
	   }
	}else{
		return null;	
	}
}
function emparejar(cantMenos){
	var fin = getObj("ieend");
	var izq = getObj("atrizq");
	var med = getObj("atrmed");
	var der = getObj("atrder");
	var a = fin.offsetTop;
	if(Boolean(izq))	izq.style.height = a - cantMenos;
	if(Boolean(med)) 	med.style.height = a - cantMenos;
	if(Boolean(der)) 	der.style.height = a - cantMenos;
}