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[İmran Tanrikolu]

I couldn't solve this question. Does anyone know the solution?

[Robin Arnez]

You need to put a newline after the ​`​`​`​

[Robin Arnez]

In what context? This would be Nat.add_right_cancel

[Robin Arnez]

You mean natural number game?

[Robin Arnez]

You need to start with induction on n