the constraints are stated as beteen 1 and 12, therefore the solution does not need to account for negative numbers

It works until there is NaN or Inf in ls or there is loss of precision.

you are wrong. Only 1 "if" will return a value here.

no me gusta esta solucion, porque si el mes es 2 abria tendria que devolver 1,2 , 3 y 4. ya que 2 es un mes menor a 12, a 9, a 6 y a 3. y la idea es devolver 1 mes, corrijanmen si me equivoco

Thank you

What happened when user enter 0 or 13? Not degenerating answer but question did not explain it well for such conditions. Good solution by the way

huh never think of this

No, I havn't received any call stack limit errors with this recursive solution.

hardcode for life!