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: Ed had 2 more marbles than Doug. Doug lost some of his marbles at the playground. Now Ed has 19 more marbles than doug. 

 Question: How many marbles did Doug lose?
Example Output: 17

Example Input: Context: At the arcade Dave had won 13 tickets. If he used 8 to buy some toys and 18 more to buy some clothes 

 Question: How many more tickets did Dave use to buy clothes than he did to buy toys?
Example Output: 10

Example Input: 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?
Example Output:
4