Task: Question Understanding
Input (English): Passage: The conflict is often referred to by different names, most commonly the Russo-Polish War, with the term Russia replacing the term Muscovy. In Polish historiography, the wars are usually referred to as the Dimitriads: the First Dymitriad  and Second Dymitriad  and the Polish-Muscovite War , which can subsequently be divided into two wars of 1609-1611 and 1617-1618, and may or may not include the 1617-1618 campaign, which is sometimes referred to as Chodkiewicz  Campaign. According to Russian historiography, the chaotic events of the war fall into the "Time of Troubles". The conflict with Poles is commonly called the Polish Invasion, Polish Intervention, or more specifically the Polish Intervention of the Early Seventeenth Century.
Question: How many years long was the longest war?
Output (English): number