ABC125C
C - GCD on Blackboard
https://gyazo.com/be7a37e747fc2d81355ee27815fa105a
Thoughts.
If the remaining gcd after removing one is 1, then it's 1 no matter what.
Because gcd can never be greater than its argument.
In other words, "Find the maximum value of gcd with one removed."
This is obsolete rule prohibiting match-ups between wrestlers from the same group of stables.
Cumulative product from left to right is OK
Official Explanation
Same policy
He's using 0 as a sentry.
$ \gcd(0, X) = \gcd(X, 0) = X
Python standard gcd also behaves this way
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