var noOfBonusTracks = 0;
function checkAlbum(){
	var noOfCheckedBoxes = 0;
	var noOfCheckboxesInForm = 0;
	
	for(var i=0; i<document.album.elements.length; i++){
		if(document.album.elements[i].type == 'checkbox'){
			noOfCheckboxesInForm++;
		}
	}
	
	var noOfRegularTracks = noOfCheckboxesInForm - noOfBonusTracks;
	
	for(var i=0; i<noOfRegularTracks; i++){
		if(document.album.elements[i].checked == true){
			noOfCheckedBoxes++;
		}
	}
	
	var indexOfBonusTracks = noOfCheckboxesInForm - noOfBonusTracks;
	
	if(noOfCheckedBoxes == noOfRegularTracks){
		for(var i=indexOfBonusTracks; i<noOfCheckboxesInForm; i++){
			document.album.elements[i].disabled = false;
			document.album.elements[i].checked = true;
		}
	}
	else {
		for(var i=indexOfBonusTracks; i<noOfCheckboxesInForm; i++){
			document.album.elements[i].checked = false;
			document.album.elements[i].disabled = true;
		}
	}
}