Note that the IMO contestants get 4½ hours for all six problems, average 45 minutes per problem. These are really good young mathematicians here.
My mistake: they actually got 4½ hours for problems 1, 2, and 3, then another 4½ hours for problems 4, 5, and 6, on consecutive days. So that’s actually an hour and a half per problem. Sorry.
Now I don’t feel so bad about having wrestled with the second-easiest problem for 4 hours.
If you want to see worked solutions to the problems, they can be found on any number of math forums. Just type “2013 IMO problems” into your search engine of choice. Here for example is a discussion of Problem 1, the one I was diddling with when I should have been spackling the downstairs bathroom.