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.
Q: Passage: On 19 April 1918, Detachment Brandenstein took over the town of Lahti. The German troops advanced from the east-southeast via Nastola, through the Mustankallio graveyard in Salpausselka and the Russian garrisons at Hennala. The battle was minor but strategically important as it cut the connection between the western and eastern Red Guards. Local engagements broke out in the town and the surrounding area between 22 April and 1 May 1918 as several thousand western Red Guards and Red civilian refugees tried to push through on their way to Russia. The German troops were able to hold major parts of the town and halt the Red advance. In total, 600 Reds and 80 German soldiers perished, and 30,000 Reds were captured in and around Lahti.
Question: How many days was the time span where local engagements broke out in the town and surrounding area as several thousand western Red Guards and civilian refugees tried to push through on their way to Russia?
Answer type: Number
A:
9.