I participated in the beta round #7, and my performance wasn't good and I dropped some rating points.

My first mistake was in problem B, in which I wasn't careful that "erase" parameter can be any integer. I think my solution failed for "erase -1". Well, this didn't cost me too much, as I figured it out in about 10 minutes and got it Accepted.

My second mistake, and biggest mistake was in problem C. I'm very weak in number theoretical problems (currently), and I didn't realize that this is a standard Diophantine equation, which had a very standard algorithm to solve. After some struggling, I searched the internet for some help. At last, I ended up in Shygypsy's tools, which had the code for problem. But it didn't work for negative numbers, and I wasn't good enough to figure out how to do the % operator for negative numbers. After much time spending on this problem, and writing too much unnecessary code, I could get it Accepted in 1:43.

Then I tried to solve problem D, but probably 17 minutes wasn't enough for me. It wasn't a hard problem. Palindrome prefixes can be detected in O(n) using KMP (or probably using hashing), and the rest can be done using a simple DP. Well, the solution wasn't difficult, but probably I didn't have enough self-confidence to solve it.

I have lack of self-confidence, maybe because I have lack of practice :-) I will most probably participate in next match, and I hope to gain some rating points.