Phone validator can take 8 digits starting only with 1,8,or 9

Question

import re
#your code goes here
num=int(input())
pattern=r"[189][0-9]+"
if re.match(pattern,"num"):
print('Valid')
else:
print('Invalid')

Answer 1

delete quotes from num and add ^ $ for mark start end of pattern

Answer 2

Your regular expression pattern should reflect that there must be exactly 8 digits, so 7 after the first one.
r"[189][0-9]{7}"

Answer 3

Not all these are working I have tried it