* Directory structure
- "slides" directory
-- slide files (e.g. 004_EF_The_Most_Powerful_Spell.pptx)
naming rule: [number]_AB|CD|EF_[title]([author])
- "code" directory
-- language directories (e.g. java, cpp, ...)
--- contest directories (e.g. Domestic2010, Domestic2010Practice)
---- solution files (e.g. ProblemC.java, ProblemE.java)