I bet you knew already, grandpa, that today is St Cyril's Day. He is credited with inventing the Cyrillic alphabet; at least, it's named after him. I bet you didn't know, though, (and neither did I) that the following langauges are written in the Cyrillic alphabet:
Abaza, Abkhaz, Adyghe, Aghul, Akhvakh, Archi, Avar, Azeri, Balkar, Bashkir, Belarusian, Bulgarian, Buryat, Chechen, Chukchi, Church Slavonic, Chuvash, Dargwa, Dungan, Erzya, Even, Evenki, Gagauz, Ingush, Kabardian, Kalmyk, Karakalpak, Kazakh, Komi, Koryak, Kumyk, Kurdish, Kyrghyz, Laz, Lak, Lezgi, Lingua Franca Nova, Macedonian, Mansi, Mari, Moksha, Moldovan, Mongolian, Nanai, Nenets, Nivkh, Old Church Slavonic, Ossetian, Russian, Ruthenian, Serbian, Slovio, Tabassaran, Tajik, Tatar, Turkmen, Tuvan, Tsez, Udmurt, Ukrainian, Uyghur, Uzbek, Votic, Yakut, Yukaghir, Yupik.
Bozhe moi, I haven't even heard of most of them!