You are given a math word problem and you are supposed to only use subtraction on the numbers embedded in the text to answer the following question and then only report the final numerical answer.

Example input: Context: Sam is 6 feet tall and Alex is 5 feet tall 

 Question: By how many feet is Sam taller than Alex? 
Example output: 1
Example explanation:  Sam's height - Alex's height = 6-5 = 1
Q: Context: Tiffany was collecting cans for recycling. On monday she had some bags of cans. The next day she found 4 more bags worth of cans. If she had a total of 8 bags altogether 

 Question: How many bags did she have on monday?
A:
4