This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

Ex Input:
In 121 BC, Han forces expelled the Xiongnu from a vast territory spanning the Hexi Corridor to Lop Nur. They repelled a joint Xiongnu-Qiang invasion of this northwestern territory in 111 BC. In that year, the Han court established four new frontier commanderies in this region: Jiuquan, Zhangyi, Dunhuang, and Wuwei. The majority of people on the frontier were soldiers. On occasion, the court forcibly moved peasant farmers to new frontier settlements, along with government-owned slaves and convicts who performed hard labor. The court also encouraged commoners, such as farmers, merchants, landowners, and hired laborers, to voluntarily migrate to the frontier.

Ex Output:
Who made up a majority of the people on the frontier?

Ex Input:
The Prussian Army, under the terms of the armistice, held a brief victory parade in Paris on 17 February; the city was silent and draped with black and the Germans quickly withdrew. Bismarck honoured the armistice, by allowing train loads of food into Paris and withdrawing Prussian forces to the east of the city, prior to a full withdrawal once France agreed to pay a five billion franc war indemnity. At the same time, Prussian forces were concentrated in the provinces of Alsace and Lorraine. An exodus occurred from Paris as some 200,000 people, predominantly middle-class, went to the countryside.

Ex Output:
What did the Prussian Army hold in Paris on 17 February?

Ex Input:
Von Neumann was a founding figure in computing. Donald Knuth cites von Neumann as the inventor, in 1945, of the merge sort algorithm, in which the first and second halves of an array are each sorted recursively and then merged. Von Neumann wrote the sorting program for the EDVAC in ink, being 23 pages long; traces can still be seen on the first page of the phrase "TOP SECRET", which was written in pencil and later erased. He also worked on the philosophy of artificial intelligence with Alan Turing when the latter visited Princeton in the 1930s.

Ex Output:
Who was the inventor of the merge-sort algorithm?