Task: Question Answering
Input (English): 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 Salpausselkä 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 
Output (English): 9.