What's wrong with this phone number validator regex?

Question

This is the task:
You are given a number input, and need to check if it is a valid phone number.
A valid phone number has exactly 8 digits and starts with 1, 8 or 9.
Output "Valid" if the number is valid and "Invalid", if it is not.

What is wrong with the following regex?

import re

number = input()
pattern = r"^1|8|9\d{8}

Answer 1

^(1|8|9)\d{7}$
start with 1 or 8 or 9 , next 7 digit

Answer 2

Thank you Roland 🙏