Definition: In this task, you're given a question, along with a context passage which has extra information available on certain terms mentioned in it, i.e., the proper nouns in the passage. Your job is to determine whether information from more than one term is needed to answer the question. Indicate your choice as `a` for Yes or `b` for No.
Input: Question: What country was the location of the castle that was exchanged for Dinaburg Castle? Passage:Traidenis, known for his devotion to paganism and anti-German attitude, was also successful in fighting with the Livonian Order. In 1270 he won the Battle of Karuse, fought on ice near Saaremaa, and killed Otto von Lutterberg, master of the Order. A new master, Andreas von Westfalen, sought a quick revenge, but was also killed by Traidenis. However, by 1272 the Order retaliated, attacking Semigalia and building Dinaburg Castle in 1273 on lands nominally controlled by Traidenis. Despite four siege engines used to throw stones, he was unable to capture the new fortress and had to retreat in 1278. In 1279 the order attacked Lithuanian lands, reaching as far as Kernavė, but on their way back they suffered a great defeat in the Battle of Aizkraukle. The Order's master, Ernst von Rassburg, became the third master to be killed by Traidenis. The defeat encouraged conquered Semigallians to rebel. The Semigalians, led by Nameisis, were now willing to acknowledge Lithuania's superiority and asked Traidenis for assistance. In 1281, Traidenis conquered Jersika Castle in the present-day Preiļi District, and was able to exchange it for Dinaburg Castle. However, Traidenis died soon afterwards, and assistance to Semigalians, exhausted by constant warfare, diminished. Traidenis is the first known Lithuanian duke to have died a natural death. All others before him were assassinated or killed in battle.


a