ABC109D

https://gyazo.com/1c2b233f267cb0812cd14d32d2d5bd4a

Thoughts.

This paragraph is a misunderstanding

There is no benefit to moving something that is already even.

Losses when odd numbers join even numbers.

Does it make sense to move even numbers if it's to open the way for them not to merge?

I mistakenly thought it was moving the whole mountain, but it was "moving one piece."

then the largest solution is the one that once all the coins in the odd-numbered pile are removed and two coins are dealt in each of the zero squares

You're asked to output the steps, but they don't have to be the shortest steps, just process them in order.

Official Explanation

I see in the sample that "an even number of coins were placed" includes zero coins.

Then we just move one from one odd-numbered pile to another odd-numbered pile.

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