... from 1-5 with obviously five being the most difficult and ... 17 s2, PT 21 s3, PT 22 s2&4 ... , PT 23 s3, PT 25 s2, PT ... 39 s2, PT 40 s3, PT 43 s3, PT 44 s4, ... PT 47 s3, PT 48 s4, PT ... 49 s2, PT 51 s3, PT 56 s2, PT ... s2, PT 63 s3, PT 71 s3, PT 76 s2< ...