checkar=new Array();
if(!checkar.pop){
	function arpop(){
		var ret=this[this.length-1];
		this.length=this.length-1;
		return ret;
	}

	function arpush(val){
		this[this.length]=val;
		return this.length;
	}

	function arshift(){
		var ret=this[0];
		for(var i=1; i<this.length; i++) this[i-1]=this[i];
		this.length=this.length-1;
		return ret;
	}

	function arunshift(val){
		var ret=this[0];
		for(var i=this.length-1; i>=0; i--) this[i+1]=this[i];
		this[0]=val;
		return this.length;
	}

	Array.prototype.pop=arpop;
	Array.prototype.push=arpush;
	Array.prototype.shift=arshift;
	Array.prototype.unshift=arunshift;
}