#!/usr/bin/env python3

usernames = [
    'bob',
    'alice',
    'tom'
]

passwords = [
    'bob',
    'alice',
    'tom'
]

user = input('Username: ')
pw = input('Password: ')

index = usernames.index(user)

if passwords[index] == pw:
    print('Authenticated.')
else:
    print('Incorrect username or password.')