private static int getNaturalIndex(char note) {
		switch(note) {
		case 'a': return 0;
		case 'b': return 2;
		case 'c': return 3;
		case 'd': return 5;
		case 'e': return 7;
		case 'f': return 8;
		case 'g': return 10;
		}
		return -1;
	}