A warning: although there are only bound currents in this problem, it does not mean that H=0.
There are two ways of solving the problem. First, use the Ampère’s circuital law for a suitably selected loop while keeping in mind the boundary conditions for the magnetic field at the surface of the magnet. Second, make a good use of the formula B/\mu_0=H+M.
Please submit the solution of this problem via e-mail to firstname.lastname@example.org. The second hint will appear here on 12th December 2021. From 5th December to 12th December, the base score is 0.9 pts, and from 12th December to 19th December, the base score will be 0.8 pts. For full regulations, see the “Participate” tab. The next updates of the intermediate results for the Problem 1 will be published after 13:00 GMT, 12th December 2021.