Hi admin,

I misunderstood the problem. More precisely, I replaced the sentence:

the problem set of any contest must contain at least x and at most y problems

with this one:

the problem set of any contest must contain either x or y problems

It turned out that the modified version of the problem is also solvable, and I have designed the program for submittion. Unsurprisingly, I got Wrong Answer.

Now, I will try to solve the original problem. And, admin, would you please consider to add the modified version to the ProblemSet?