Dice game login system

The end result of this is to allow a user to log in and/or register themselves for a dice game. Please post some suggestions for improvement.

import pickle

logged_in = False

with open('users.pickle', 'rb') as a_file:
    users = pickle.load(a_file)

login_or_signup = input('do you want to login or signup? ')

# sign up (creating new account)
if login_or_signup.lower() == "signup":

    create_username = input("enter a new username: ")
    create_password = input("enter a new password (Your password cannot be the same as your username !!!!!!!): ")

    if create_password in users:
        create_password = input("password taken re-enter: ")

    users[create_username] = create_password

username = input('please enter username: ')

if username in users:
    password = input("enter password: ")
    if password == users[username]:
        print("access granted")
        logged_in = True

else:
    print("access denied")

with open("users.pickle", 'wb') as f:
    pickle.dump(users, f, pickle.HIGHEST_PROTOCOL)