Right... I guess this problem was put in here for comic relief. :)

For crying out loud, the author didn't even bother to increase the limits so as to make this a 'bignum' problem... :P

This is "Осеннее первенство школьников 2003". Now you understand why it is so easy?

And yet, this problem has a higher site difficulty than Ural Steaks, which is a much more sophisticated problem than this one.   The difficulty of a problem is not necessarily related to how much code it takes to solve it, the point of problem solving is to map scenarios to programs that solve them.   It is the proper understanding of the problem where a lot of the difficulty (and most of the importance!) lies.