ai_books = { 
    "Artificial Intelligence with Python by Prateek Joshi", 
    "Artificial Intelligence Programming with Python: From Zero to Hero by Perry Xiao", 
    "Python Machine Learning by Sebastian Raschka", 
    "Hands-On Artificial Intelligence with Java for Beginners by Nisheeth Joshi", 
    "ChatGPT for Java: A Hands-on Developer's Guide to ChatGPT and Open AI APIs by Bruce Hopkins", 
    "Java Artificial Intelligence and Deep Learning by Sage Rylan" 
} 
 
java_books = { 
    "Hands-On Artificial Intelligence with Java for Beginners by Nisheeth Joshi", 
    "ChatGPT for Java: A Hands-on Developer's Guide to ChatGPT and Open AI APIs by Bruce Hopkins", 
    "Java Artificial Intelligence and Deep Learning by Sage Rylan", 
    "Big Java: Early Objects 7th Edition by Cay S. Horstmann", 
    "Effective Java by Joshua Bloch" 
} 
 
python_books = { 
    "Artificial Intelligence with Python by Prateek Joshi", 
    "Artificial Intelligence Programming with Python: From Zero to Hero by Perry Xiao", 
    "Python Machine Learning by Sebastian Raschka", 
    "A Byte of Python by Swaroop C H.", 
    "Python Crash Course by Eric Matthes" 
} 

print("1: \n",python_books - ai_books)  # Βιβλία Python που δεν είναι για AI
print("2: \n",python_books.difference(ai_books))  # Εναλλακτικός τρόπος για το ίδιο αποτέλεσμα
print("3: \n",java_books & ai_books)   # Βιβλία που είναι και για Java και για AI
print("4: \n",java_books.intersection(ai_books))  # Εναλλακτικός τρόπος για το ίδιο αποτέλεσμα
print("5: \n",(python_books-ai_books),(java_books - ai_books))  # Βιβλία Python και Java που δεν είναι για AI
print("6: \n",python_books.symmetric_difference(ai_books))  # Βιβλία που είναι είτε για Python είτε για AI, αλλά όχι και για τα δύο
book = "Artificial Intelligence with Python by Prateek Joshi"
book[book.find(" by ") + 4:]  # Εξαγωγή του ονόματος του συγγραφέα από μια συμβολοσειρά βιβλίου
print("7: \n",book[book.find(" by ") + 4:])  # Εμφάνιση του ονόματος του συγγραφέα