Given the task definition, example input & output, solve the new input case.
You are given a math word problem and you are supposed to apply an addition mathematical operator on the numbers embedded in the text to answer the following question and then only report the final numerical answer.
Example: Context: 21 children were riding on the bus. At the bus stop 5 children got off the bus while some more got on the bus. Then there were 16 children altogether on the bus. 

 Question: How many children got on the bus at the bus stop?
Output: 0
Number of children who got on -> 21 - 5 + x = 16 , x = 0, hence no one got onto the bus

New input case for you: Context: Paul got a box of some crayons for his birthday. By the end of the school year he had either lost or given away 551 of them and only had 177 left. 

 Question: How many crayons did he get for his birthday?
Output:
728