I started using TopCoder Web Arena to upsolve older SRMs, since moving to a new practice room takes too long while using Java Applet (could be my Internet issue).

Here's the problem. Large integers (about $$$10^{16}$$$) can't be shown correctly in the Web Arena.

Example:

And as you can see, the verdict shows N/A instead of Correct or Wrong Answer. It's very weird.

Be aware of this hmehta.