Slovak genitive in u

Slovak is the only Slavic language I am aware of that has genitive singular in u for masculine animate nouns ending in a. All other Slavic languages have a y/e there instead.

Slovak: Dostal som rozkaz od komunistu.

Czech: Dostal jsem rozkaz od komunisty.

Polish: Dostałem rozkaz od komunisty.

English: I received an order from a/the communist.

The u (in Polish ę) ending, though, is typical for both masculine animate nouns ending in a and feminine nouns with the same ending:

Slovak: Videl som tam komunistu.

Czech: Viděl jsem tam komunistu.

Polish:  Widziałem tam komunistę.

English: I saw a/the communist there.