I decided to make a grammar library in C#, for inflecting nouns, adjectives, pronouns and verbs. I thought I'd finish the project in a week or two, but the Russian language turned out to be so much more complicated than I ever imagined, even though it's my first language.
Traditionally, as you would learn from the textbooks, there are "only 3 declensions". But the thing is, that's the optimal number of declensions for humans to learn. As you dig deeper, and eliminate the "human intuition" factor, you end up with... approx. 4 558 657 distinct declensions. But, unfortunately, even that amount doesn't cover all the words...