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.

Input: Consider Input: A teacher had 6 worksheets to grade . If she graded 4 , but then another 18 were turned in , how many worksheets would she have to grade ?

Output: 20


Input: Consider Input: Oliver had 35 dollars . For his birthday he got 50 more dollars but spent 84 on a new game . How much money does he have now ?

Output: 1


Input: Consider Input: At the schools book fair Sam bought 13 adventure books and 17 mystery books . If 15 of the books were used , how many new books did he buy ?


Output: 15