Given a math word problem, answer the following question. You might need to apply addition or subtraction mathematical operators on the numbers embedded in the text to answer the question and then only report the final numerical answer.

Input: Consider Input: while playing a video game ned lost 13 lives . now he has 70 lives . how many lives did ned have at the start ?

Output: 83

Input: Consider Input: a clown had 16 balloons . he gave 4 away at a party . how many balloons does he still have ?

Output: 12

Input: Consider Input: you have 7 balloons and your friend has 5 balloons . what 's the difference of the number of your balloons and your friend 's balloons ?
Output: 2