https://csacademy.com/

https://open.kattis.com/languages

https://www.codewars.com/kata/search/?q=&beta=false&order_by=sort_date%20desc

https://cs50.harvard.edu/python/

https://www.geeksforgeeks.org/python/python-exercises-practice-questions-and-solutions/

https://www.geeksforgeeks.org/dsa/sieve-of-eratosthenes/

https://cp-algorithms.com/algebra/sieve-of-eratosthenes.html