Can't figure out functions in Python?

Question

Python

Hello, I'm new, I couldn't find a solution to one simple problem.
It is necessary that while the user enters numbers less or more than 3, the number input is displayed again. But the problem is that if you initially enter an incorrect number, and the second time it is correct, then after the second time the number is displayed again. If you enter the wrong number two or more times, then for the third and more times everything will work fine, and the code will continue to run. I apologize for the idiotic wording of the question.

def fun():
    return int(input())

a = fun()

while a < 3 or a > 3:
  fun()
  a = fun()

Answer 1

1. Why ? why not ? 2. Why call a function 2 times in a loop? a < 3 or a > 3a != 3