Getting minimum and maximum from inputs

I do not understand what is wrong with this code. It works well for the largest, but not the smallest. And both line of codes are the same! I am new here and new to programming as well, pardon my inexperence . Please note that I need to solve this problem with these methodes as it was insructed in the chapter in the course.

largest = None
smallest = None
while True:
    num = input("Enter a number: ")
    if (num=="done"): 
        break
    else:
        try:
            num=int(num)
        except:
            print("Invalid input") 
            continue
    if(num < smallest):
        smallest = num
    elif(num > largest):
        largest = num
print("Maximum is", largest)
print("Minimum is", smallest)

You shouldn't set smallest and largest to None, because you can't compare this with a number.

Instead, you should set them both to the first input. Then you can compare additional numbers to them. And if only one number is entered, it will be the mamimum and minimum.

I've moved reading the number into a function, to avoid repeating the validation loop in both places.

def get_number():
    while True:
        num = input("Enter a number: ")
        if num == "done":
            return num
        try:
            num = int(num)
            return num
        except:
            print("Invalid input")

smallest = get_number()
largest = smallest
if smallest == "done":
    print("At least one number must be entered")
else:
    while True:
        num = get_number()
        if num == "done":
            break
        if num < smallest:
            smallest = num
        elif num > largest:
            largest = num
    print("Maximum = ", largest)
    print("Minimum = ", smallest)

Test results:

$ python testminmax.py
Enter a number: 7
Enter a number: 2
Enter a number: bob
Invalid input
Enter a number: 10
Enter a number: 4
Enter a number: done
Maximum =  10
Minimum =  2