How to make users only enter integer values in Python program

Question

I have a homework assignment that I am very confused about. I have to write a program allowing users to input the number of eggs that they are buying. The program will then

Answer 1

Let the user enter anything he wishes, and warn only if it wasn't an integer:

try:
    num = int(input("enter number: "))
except ValueError:
    print("you must enter an integer")

This is the Pythonic way to do it, after all it's "Easier to ask forgiveness than permission".