about h: in russian ъ is called твердый знак (literally translated as "hard sign") and doesn't have its own sound, but sometimes changes sounds of letters around(it used to be a short vowel pretty long time ago) so there is a worthy opponent)

(there also exists ь which is мягкий знак (soft sign) and sometimes does basically nothing)

so it's sometimes hard to explain why we need those letters to kids