Teacher: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.
Teacher: Now, understand the problem? Solve this instance: Passage: Eventually the Commonwealth Sejm voted to raise the funds necessary to resume large scale military operations. The final attempt by Sigismund and Wadysaw to gain the throne was a new campaign launched on 6 April 1617. Wadysaw was the nominal commander, but it was hetman Chodkiewicz who had actual control over the army. In October, the towns of Dorogobuzh and Vyazma surrendered quickly, recognizing Wadysaw as the tsar. However, the Commonwealth forces suffered defeats between Vyazma and Mozhaisk, and Chodkiewicz's plans for a counterattack and an advance to Moscow failed. Wadysaw did not have enough forces to advance to Moscow again, especially because the Russian support for the Poles was all but gone by that time. In response to Wadysaw's invasion, the burghers of Smolensk revolted against Polish rule, and the Polish troops had to fight their way back as they retreated from the city. However, in 1617 Polish forces, besieged in Smolensk by Russian forces, were relieved by Lisowczycy, when Russian forces retreated to Bely soon after receiving news that Lisowczycy, then commanded by Stanisaw Czapinski, had appeared in the area. In 1618 Petro Sahaidachny's campaign against Muscovy resulted in sacking numerous forts such as Putivl, Kursk, Yelets, and others. Together with Chodkiewicz he laid siege to Moscow in September 1618. Due to unclear reasons, both Hetmans failed to take the city. Negotiations began and a peace treaty was signed in 1618.
Question: How many months after the new campaign was launched did the the towns of Dorogobuzh and Vyazma surrender?
Answer type: Number
Student:
6.