Can you give me some example problems for these topics (not too hard, just example)

- Extended euclidean algorithm
**This one: Ax + By = GCD(A,B)** - Sieve of Eratosthenes in a given range [L,R]
- Modular Inverse **like pow(a,m — 2) have same remainder as pow(a,-1) if m is a prime number **
- Do you have any problems for need to use PRIME NUMBERS to get Accepted?

And can you give me some important topics of Number Theory which are necessary for Competitive Programming? Thank you!

đéo