Task: Question Answering
Input (English): Passage: In a letter to his friend and landlord Johann Lorenz Hagenauer (1712–1792), a prominent Salzburg merchant, written after the tour, Leopold quotes the German diplomat Friedrich Melchior, Baron von Grimm, who after hearing the children play had said: "Now for once in my life I have seen a miracle: this is the first". Leopold believed that it was his duty to proclaim this miracle to the world, otherwise he would be "the most ungrateful creature". He was said to have described Wolfgang as "The miracle which God let be born in Salzburg." Mozart biographer Wolfgang Hildesheimer has suggested that, at least in the case of Wolfgang, this venture was premature: "Too soon, [the] father dragged [the] son all over Western Europe for years. This continual change of scene would have worn out even a robust child..." However, there is little evidence to suggest that Wolfgang was physically harmed or musically hindered by these childhood exertions; it seems that he felt equal to the challenge from the start.Leopold wanted to begin the tour as soon as possible—the younger the children were, the more spectacular would be the demonstration of their gifts. The route he intended to take included southern Germany, the Austrian Netherlands, Paris, Switzerland and possibly northern Italy. The London leg was only added after urgings during the Paris visit, and the eventual Dutch trip was an unplanned detour. The plan was to take in as many princely European courts as possible, as well as the great cultural capitals—Leopold was relying on his professional musical network and on his more recent social contacts to obtain invitations from the royal courts. Practical assistance came from Hagenauer, whose trading connections in the major cities would supply the Mozarts with what were effectively banking facilities. These would enable them to obtain money en route, while waiting for the proceeds from their performances to accumulate.Wolfgang prepared for the tour by perfecting himself on the violin, which he had learned to play apparently without any tutelage whatsoever. As for more general preparation, the children delighted in making music together, something they never lost. On tour, even during the busiest travelling days they would fit in their daily practice, appearing to thrive on the hectic schedule. Before the journey could begin, Leopold needed the consent of his employer, the prince-archbishop. Leopold had only been appointed deputy Kapellmeister in January 1763; nevertheless the archbishop's consent to an extended leave of absence was granted, on the grounds that the Mozarts' successes would bring glory to Salzburg, its ruler, and to God. 
Question: What is the last name of the person who needed the consent of his employer before taking a journey?
Output (English): Mozart.