Q: This task involves creating answers to complex questions, from a given passage. Answering these questions, typically involve understanding multiple sentences. Make sure that your answer has the same type as the "answer type" mentioned in input. The provided "answer type" can be of any of the following types: "span", "date", "number". A "span" answer is a continuous phrase taken directly from the passage or question. You can directly copy-paste the text from the passage or the question for span type answers. If you find multiple spans, please add them all as a comma separated list. Please restrict each span to five words. A "number" type answer can include a digit specifying an actual value. For "date" type answers, use DD MM YYYY format e.g. 11 Jan 1992. If full date is not available in the passage you can write partial date such as 1992 or Jan 1992. If you find multiple spans, please add them all as a comma separated list. Please restrict each span to five words.
Passage: In order to regain control of the custom duties, the emperor John VI Kantakouzenos made preparations to lower Constantinople's duties and most tariffs to undercut the Genoese in Galata. Still recovering from the civil war of 1341-1347, the emperor, with great difficulty, raised 50,000 hyperpyra from private sources for a shipbuilding program for the expected war to come. When the tariffs and custom duties were finally lowered, merchant shipping coming through the strait bypassed Genoese Galata and diverted their ships across the Golden Horn to Byzantine Constantinople. The Genoese, financially hard-hit from this policy, declared war on the Empire, and in August 1348, a flotilla of ships sailed across the Horn and attacked the Byzantine fleet; despite their large scale preparations, the Byzantine fleet was destroyed by early 1349. The Byzantines retaliated by burning wharves and warehouses along the shore and catapulted stones and burning bales of hay into Galata, setting major parts of the city on fire. After several weeks of fighting, plenipotentiaries from Genoa came and negotiated a peace agreement. The Genoese agreed to pay a war indemnity of 100,000 hyperpyra and evacuated the land behind Galata which they illegally occupied; last, they promised never to attack Constantinople. In return the Byzantines surrendered nothing, but the Genoese custom duties remained in effect.
Question: How many years did the civil war of 1341-1347 last?
Answer type: Number
A:
6.