Input: Article: To the southwest, the principality of Halych had developed trade relations with its Polish, Hungarian and Lithuanian neighbours and emerged as the local successor to Kievan Rus'. In 1199, Prince Roman Mstislavich united the two previously separate principalities. In 1202 he conquered Kiev, and assumed the title of Grand Duke of Kievan Rus', which was held by the rulers of Vladimir-Suzdal since 1169. His son, Prince Daniil (r. 1238–1264) looked for support from the West. He accepted a crown as a "Rex Rusiae" ("King of Russia") from the Roman papacy, apparently doing so without breaking with Constantinople. In 1370, the patriarch of the Eastern Orthodox Church in Constantinople granted the King of Poland a metropolitan for his Russian subjects. Lithuanian rulers also requested and received a metropolitan for Novagrudok shortly afterwards. Cyprian, a candidate pushed by the Lithuanian rulers, became Metropolitan of Kiev in 1375 and metropolitan of Moscow in 1382; this way the church in the Russian countries was reunited for some time. In 1439, Kiev became the seat of a separate "Metropolitan of Kiev, Galich and all Rus'" for all Greek Orthodox Christians under Polish-Lithuanian rule.

Now answer this question: Who united the two previously separated principalities?

Output: Prince Roman Mstislavich

Input: Article: Waste management including sewage treatment, the linked processes of deforestation and soil degradation, and climate change or global warming are the major environmental problems in Nigeria. Waste management presents problems in a mega city like Lagos and other major Nigerian cities which are linked with economic development, population growth and the inability of municipal councils to manage the resulting rise in industrial and domestic waste. This huge waste management problem is also attributable to unsustainable environmental management lifestyles of Kubwa Community in the Federal Capital Territory, where there are habits of indiscriminate disposal of waste, dumping of waste along or into the canals, sewerage systems that are channels for water flows, etc.

Now answer this question: What is the largest Nigerian city?

Output: Lagos

Input: Article: Unique to the development of Dutch is the collaps of older ol/ul/al + dental into ol + dental, followed by vocalisation of pre-consonantal /l/ and after a short vowel, creating the diphthong /ɑu/ e.g., Dutch goud, zout and bout corresponds with Low German Gold, Solt, Bolt; German Gold, Salz, Balt and English gold, salt, bold. This is the most common diphthong along with /ɛi œy/. All three are commonly the only ones considered unique phonemes in Dutch. The tendency for native English speakers is to pronounce Dutch names with /ɛi/ (written as ij or ei) as /aɪ/, (like the English vowel y) which does not normally lead to confusion among native listeners, since in a number of dialects (e.g. in Amsterdam) the same pronunciation is heard.

Now answer this question: What's the term we use for the type of sound made for two vowels in words like the Dutch "goud" or "zout"?

Output:
diphthong