Trouble understanding a datagram problem's solution.

Here is an attachment of the problem I am having trouble with:

http://i43.tinypic.com/2h34eiw.png

I understand the question and most of the solution and was able to come up with most of the answer correctly. At the end however, the problems asks to list the order in which the packets arrive....

My solution says 1 -> 4 -> 2 -> 5 -> 3

However, the solution in the attached image says the order is the exact opposite, I was wondering if anyone can help me understand if the attached solution is correct, and if so, why does it appear to be backwards?


Thanks in advance.