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.

Ex Input:
Context: Dave had 24 files and 13 apps on his phone. After deleting some apps and files he had 17 apps and 21 files left. 

 Question: How many files did he delete?

Ex Output:
3


Ex Input:
Context: Dan has $ 5. He bought a chocolate for $ 3 and a candy bar for $ 7. 

 Question: How much money did he spend to buy candy bar than he did to buy chocolate?

Ex Output:
4


Ex Input:
Context: At the arcade Dave had won 14 tickets and lost 2 tickets. If he used 10 to buy some toys 

 Question: How many tickets did Dave have left?

Ex Output:

2