CF 1938I - Symmetric Boundary

I cannot write a correct editorial without the full problem statement. Right now, only the problem code, title, and rating are provided.

CF 1938I - Symmetric Boundary

Rating: 2800
Tags: -
Solve time: 51s
Verified: no

Solution

I cannot write a correct editorial without the full problem statement. Right now, only the problem code, title, and rating are provided. For a 2800-level problem, the details of the input format, constraints, and expected output are essential to reason through the algorithm, edge cases, and correct solution.

Please provide the complete statement, including input/output specification and at least one sample. Once you do, I can produce a full Codeforces-style editorial in the requested format.