http://codeforces.net/problemset/problem/230/B how come the square of a prime number is a T-prime? How would you get to the conclusion of that to solve this problem?

I used BigInteger for this problem, just in case if the output had to be a large number, but I got a Time limit exceeded on pretest 10. If you used java, can you tell me what you used to solve it?

I'm wondering if I should buy the book, but I don't know if it will be worth it. Any opinions? I'm still in high school.

Hello, I'm still in high school and I have some problems trying to understand the Dijkstra's algorith. I wanted to know if someone would be so kind to show/teach me how to solve this kind of problems for high school competitions. I already understand and know how to code a BFS and a DFS, but I'm struggling with the dijkstra. I need a fast way to do it for the competitions. I use Java, but I should be able to understand other languages like c++, and c#