function r_c(){
	var a = document.getElementById('maincontainer').childNodes;
	var w = 0;
	for(var i=0;i<a.length;i++){
		if(a[i].className=='c1' || a[i].className=='c2' || a[i].className=='c3')w+=a[i].offsetWidth+14;
		
	}
	document.getElementById('maincontainer').style.width=w+"px";
}