//setCheckers(600, 600);
setCheckers(580, 540);

function setCheckers(bWidth:Number, bHeight:Number):Void {
	var xPos:Number = 0;
	var yPos:Number = 0;
	var mWidth:Number = 30;
	var mHeight:Number = 30;
	var cols:Number = Math.floor(bWidth/mWidth);
	var rows:Number = Math.floor(bHeight/mHeight);
	for (var n:Number = 0; n < rows; n++) {
		for (var t:Number = 0; t < cols; t++) {
			if ((n + t) % 2 == 0) {
				var mcType:String = "a";
			} else {
				var mcType:String = "b";
			}
			var id:Number = n * cols+ t;
			var _mc:MovieClip = this.attachMovie(mcType, "mc"+id, id);
			_mc._x = xPos + mWidth * t;
			_mc._y = yPos + mHeight * n;
		}
	}
}