Create my first program in python

#program apa yg mau dibuat harus ada if dan loop:
#1. membuat login
#2. membuat existing account
#3. terddapat dua menu login dgn existing account dan create new account
#4. setelah login pilih menu ada tiga pilihan penjumlahan, pengurangan dan perkalian selain itu langsung exit

# perlu beberapa perbaikan terutama di mekanisme jika pass dan username salah berkali kali (done dengan cara balik k menu utama)
print("welcome to my first program")
print('============================')
def main_menu():
    print('choose menu: ')
    print('1. Create new account')
    print('2. login with existing account')
    print('choose 1 or 2 to input your choice: ')
    global menu
    menu = input()
    if menu == '1':
        make_account()
    else:
        login()
def make_account():
    #create global variable
    global password
    global username
    print('input your username: ')
    username = input()
    print('input your password: ')
    password = input()
    if len(password) < 4:
        print('password must be at least 4 words please try again: ')
        password = input()
        print('account succesfully created')
        main_menu()
    else:
        main_menu()
def login():
    print(username)
    print(password)
    print('what is your username: ')
    username_existing = input()
    print('what is your password: ')
    password_existing = input()
    if (password_existing != password):
        print('try again back to main menu')
        main_menu()
    else:
        print('sucess')
        main_program()

def main_program():
    print('==============================')
    print('1. sum')
    print('2. multipication')
    print('3. sum more than 2 numbers')
    print('4. exit')
    print('choose menu: ')
    choice = input()
    if choice == '1':
        #calling sum menu
        sum()
    elif choice == '2':
        #calling multipication menu
        multipication()
    elif choice == '3':
        #calling sum_numbers function
        sum_number()
    else:
        #exit program
        print('thank you for trying my program !!!')

def sum():
    print('input first number: ')
    first_number = int(input())
    print('input second number: ')
    second_number = int(input())
    result = first_number + second_number
    print('here is your result' +' '+ str(result))

def multipication():
    print('input first number: ')
    first_number = int(input())
    print('input second number: ')
    second_number = int(input())
    result = first_number * second_number
    print('here is your multipication result' +' '+ str(result))

def sum_number():
# define list variable
    print('input your number and if u want to finish add 0')
    numbers = []
    while True:
        print('input ur numbers' + ' ' + str(len(numbers) + 1)+ ':')
        input_numbers = int(input())
        if input_numbers == 0:
            break
        numbers =numbers + [input_numbers]
    print('here is your numbers:')
    print(numbers)
    result = 0
    for input_numbers in numbers:
        result += input_numbers
    print(result)
    main_program()

#calling first function to run main menu
main_menu()