# Break the Code

In his dream, Chris coded a recursive function in Python :

 1 2 3 4 5 def rec(n): if n <= 0: return 0 return 3 + rec(rec(n - _)) 

Which of the following, when substitute to _ in the $$5^{\text{th}}$$ line will lead to an infinite loop for some integer parameter $$n$$?

×