My friends from Saratov are building a new system for hosting contests and beyond. They aim for everything there to be available both in English and in Russian. Today was its second beta-test, which was a contest under ACM ICPC rules for 2 hours with 3 problems. Results: http://codeforces.com/contest/2/standings. Problems: http://codeforces.com/contest/2.
Problem B is very nice. I scratched my head for a long time before getting it, yet the idea is very simple and beautiful. I won't spoil it yet - I hope you'll enjoy solving it as well :)
Problem C turned out to be a tough implementation problem for me (I solved a system of two quadratic equations on 2 variables by eliminating the squares to get a linear equation, substituting one variable from that linear equation into one of quadratic equations, and solving the result. This required a lot of care about precision issues and corner cases, and took an hour). However, I have a feeling that it is doable by some binary/ternary search. Any ideas?