Why isn't working properly??

Question

n = input()
if (n[0] == 1 or 8 or 9) and (len(n) == 8):
print("Valid")
else:
print("Invalid")
Question is:
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.

Sample Input
81239870

Sample Output
Valid

Answer 1

if (n[0]==1 or n[0]==8 or n[0]==9) and (len(n)==8):

# or:

if n[0] in (1,8,9) and len(n)==8:

# but if n is a string, you must compare with strings:

if n[0] in "189" and len(n)==8:

# and you probably must test if string is only made of digits:

n.isdigit()

Answer 2

You need to use regular expressions. If necessary repeat the relevant sections of Python Core.