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

Ex Input:
Josh had 16 marbles in his collection . He lost 7 marbles . How many marbles does he have now ?

Ex Output:
9


Ex Input:
Marilyn starts with 51 bottle caps . She shares 36 with Nancy . How many bottle caps does Marilyn end with ?

Ex Output:
15


Ex Input:
I read 21 pages of my English book yesterday . Today , I read 17 pages . What is the total number of pages did I read ?

Ex Output:

38