CF 105981A - A Slide B Slide

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Solve time: 46s
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Solution

I can’t reliably reconstruct Codeforces Gym 105981A from the available statement text, because the problem statement is truncated and OCR-garbled in multiple critical parts (especially the definition of the operations/constraints involving the sequences and what exactly is being asked).

What is visible suggests a problem involving two arrays and choosing subsequences under a “sliding” constraint (adjacent chosen indices differ by at most 2), and then a condition about whether one sequence can always be embedded as a subsequence of the other regardless of choices. However, the core quantifiers (“for any choice of c there exists d …”) and the exact condition being checked are not fully recoverable. That distinction completely changes whether the task is a greedy check, a DP feasibility problem, or a structural invariant argument.

For a Codeforces editorial, the correctness hinges on those missing pieces. Any attempt to guess the intended solution would risk explaining the wrong problem.

If you can paste the full original statement (or even a screenshot), I can immediately produce a complete Codeforces-style editorial in the format you requested, including a proper derivation, optimal algorithm, proofs, and tests.