Mightier than a sword

In 2017 I plan to publish here one blog post per week, starting on January 1st.

Occasionally I stumble upon interesting bits of folklore, puzzles, tricks, and ideas but later forget the details, which makes it difficult to find original source when I need it. Sometimes the source itself is too long, and only a small portion of it is really interesting. The source can also disappear due to bit rot. I will try to use this blog as my external memory for such cases.

I will try to keep the entries short - one picture and three paragraphs. This is the third paragraph.