How to select elemts from a list randomly

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Python

random

I have a list
a = [1,2,3,4,5,6,7,89,34,654,354,84,6845,351,68,5,645,645,5312,65]

I want to randomly sample 8 elements from this list, so I use the following code

`import random
random.seed(1)
b = random.sample(a,8)`

Now I want to randomly sample 5 elements from the list again, but these 5 elements should not include any of the 8 elements sampled earlier.
How can I achieve that?

Thanks for the help!

What I have tried:

I have already mentioned it in the question