Goodnight! Friday task.
Having looked through puzzles on Habré, I remembered one rather nontrivial one. It is necessary to draw a shape:
(1) can not be carried out on the same line twice
(2) it is possible to
tear off a pen / pencil only
Be creative! Take a friend and argue for a couple of bottles of beer, who is faster!
PS: there are two solutions I know of, the most elegant one
PPS: who decided, share your impressions, but let others enjoy it! Do not lay out the solution immediately!