# Let us print a friendly message
print('Hello, world!')

# Variables store data so you can use it later
name = 'Alice'
print(name)

# Use input() to ask the user a question
user_food = input('What is your favorite food? ')
print('Yum! I like', user_food, 'too.')

# Math is easy in Python
a = 5
b = 3
sum_ab = a + b
print('5 plus 3 is', sum_ab)

# Python can do more than just print text.
# It can store different types of data.

age = 21
height = 1.75
is_student = True
print('Age:', age)
print('Height (meters):', height)
print('Student status:', is_student)

# You can put several things together in a list.
colors = ['red', 'green', 'blue']
print('Favorite colors:', colors)

# Access items in a list using square brackets.
print('First color:', colors[0])
print('Second color:', colors[1])

# Use input to build your own list
animal_1 = input('Name an animal: ')
animal_2 = input('Name another animal: ')
animals = [animal_1, animal_2]
print('Your animals:', animals)

# Lists can be changed after you create them.
colors.append('yellow')
print('New colors list:', colors)

# Remove an item from a list
colors.remove('green')
print('Colors after removing green:', colors)

# Sometimes things go wrong. Let us handle errors.
try:
    colors.remove('purple')
except ValueError:
    print('Could not find purple!')
    

# You can repeat actions with loops.
for color in colors:
    print('Color:', color)
    

# List comprehensions are a quick way to create new lists.
squared = [x * x for x in range(5)]
print('Squares:', squared)

# Sort a list in alphabetical order.
colors.sort()
print('Sorted colors:', colors)

# Combine two lists together.
combined = colors + animals
print('All items:', combined)

# Real-world data: make a shopping list
shopping = []
for i in range(3):
    item = input(f'Enter item {i+1}: ')
    shopping.append(item)
print('Your shopping list:', shopping)

# Mini-Project: Find the longest word in your shopping list
longest = ''
for word in shopping:
    if len(word) > len(longest):
        longest = word
print('The longest word on your list is:', longest)

# Best practice: check before removing items
if 'milk' in shopping:
    shopping.remove('milk')
else:
    print('Milk was not found in the shopping list.')
print('Shopping list now:', shopping)

# Common mistake: spelling errors
# watch for spelling differences in item names
if 'bread' in shopping:
    print('Bread found!')
else:
    print('Bread is missing. Check your spelling!')
    

# Tips: Make a backup of your list using copy()
backup = shopping.copy()
shopping.clear()
print('Backup:', backup)
print('Cleared shopping:', shopping)

# Challenge: practice with your own list
my_list = []
for i in range(2):
    word = input('Add anything: ')
    my_list.append(word)
print('Your list:', my_list)