The Czechs' language separated from other Slavic tongues into what would later be called Old Czech by the thirteenth century, a classification extending through the sixteenth century. Its use of cases differed from the modern language; although Old Czech did not yet have a vocative case or an animacy distinction, declension for its six cases and three genders rapidly became complicated (partially to differentiate homophones) and its declension patterns resembled those of <answer>Lithuanian</answer> (its Balto-Slavic cousin).
What other language did Old Czech's declension patterns resemble?
Lithuanian