The SOS page

For the (not-so unlikely) case of some of the essential web services being down, you can continue after downloading intermediate results here. There may be some missing images and broken links, but the essential information should be still available.
 
 

A

back to excercise A

B

back to excercise B

C

back to excercise C

D

back to excercise D

E

back to excercise E