Array.prototype.valueExist = function(value){
	for (var key in this) {
		if (this[key] == value) {
			return true;
		}
	}
	
	return false;
};

Array.prototype.first = function () {
	return(this[0]);
};

Array.prototype.last = function () {
	return(this[this.length - 1]);
};

Array.prototype.clear = function(){
	this.length = 0;
};