1wyckoffs: 2- "a" 3- "a" 4- "a" 5- "a" 6- "a" 7- "a" 8- "a" 9- "a" 10- "a" 11- "a" 12- "a" 13- "a" 14- "a" 15- "a" 16- "a" 17- "a" 18- "b" 19- "b" 20- "b" 21- "b" 22- "b" 23- "b" 24- "b" 25- "b" 26- "b" 27- "b" 28- "b" 29- "b" 30