olly's code

newUser = input("Do you already have an account? ")
username = [0,1,2]
password = [0,1,2]
if newUser == "no":
    newUsername = 1
    newPassword = 123
    while username.count(newUsername) >= 1:
        newUsername = input("Choose a username ")
        if username.count(newUsername) >= 1:
            print("Sorry, that username is taken")
    while len(newPassword) < 8:
        print("Enter a password that only you can know, it must be more than 8 characters long")
        newPassword = input("Choose a password ")
        if len(newPassword) < 8:
            print("More than 8 characters...")
    lenUsernameList = len(username)
    username[lenUsernameList + 1] = newUsername
    password[lenUsernameList + 1] = newPassword
    print("If you're curious, your user number is " + str(lenUsernameList + 1))
else:
    loginUsername = ""
    loginPassword = ""
    while username.count(loginUsername) == 0:
        loginUsername = input("Enter your username: ")
        if username.count(loginUsername) == 0:
            userNumber = username.index(loginUsername)
            print("Your username has been found")
    while password.count(loginPassword) == 0 and password.index(loginPassword) != username.index(loginUsername):
        loginPassword = input("Enter your password: ")
        if password.index(loginPassword) == username.index(loginUsername):
            print("You have been logged in")