I had the feeling that something was missing! Thanks :D

WTF did I just write... yeah, of course. Edited. Still, it'd be nice to have as unusual postcards as possible :D

Exactly. A bit different from standard ACM/ICPC/CF/TC problems.

О, классно. А каким критериям он должен удовлетворять (язык, местоположение)?

Участвуйте вдвоем. У нас тоже команда из двух человек.

Send HTTP request, with Accept: text/tattoo and play a little game with monster :) Pretty easy.

Send an HTTP request to the page using the HEAD method. Actually I haven’t even tried other methods, so maybe any method works. Anyway, here’s an example (with extraneous headers removed for brevity):

HEAD /2013/real/problems/h.html HTTP/1.1
Host: ipsc.ksp.sk

HTTP/1.1 200 OK
H2: A blue monster approaches you and says: "I know the word you need for H2. But I won't talk to you unless you feed me first. I'm in the mood for some dessert... its name doesn't matter, but it must contain chocolate."

Send a cookie with ‘chocolate’ in the value (if it doesn’t contain ‘chocolate’, you get the same response as before):

HEAD /2013/real/problems/h.html HTTP/1.1
Host: ipsc.ksp.sk
Cookie: name=chocolate

HTTP/1.1 200 OK
H2: "Yum! All right, if you answer this question, and do it quickly, I'll tell you the answer for H2."
H2-Question: How much is 665 plus 192?
H2-Answer: (your answer)

You need to resubmit the request with an additional request header H2-Answer: 857. If you try to answer by hand, you’ll get something like:

H2: "Too slow! Try again!"
H2-Question: How much is 265 plus 29?
H2-Answer: (your answer)

So you write a program and get:

H2: "Correct! The word you're looking for is CLASSIFICATION."

First, we make a HTTP HEAD (or HTTP GET) request and read the head of the response. It is the “head of the slave”, because the “slave” is defined here: “problem statement is the slave we sent to you, carrying the secret message”.

sh$ curl -I ipsc.ksp.sk/2013/real/problems/h.html
HTTP/1.1 200 OK
<...>
H2: A blue monster approaches you and says: "I know the word you need for H2. But I won't talk to you unless you feed me first. I'm in the mood for some dessert... its name doesn't matter, but it must contain chocolate."

A “dessert with chocolate” is cookies, or, in our case, HTTP cookies. The name of a cookie doesn’t matter, but the cookie itself must contain the “chocolate” substring.

sh$ curl -b 'some=bbbchocolateaa' -I ipsc.ksp.sk/2013/real/problems/h.html
HTTP/1.1 200 OK
<...>
H2: "Yum! All right, if you answer this question, and do it quickly, I'll tell you the answer for H2."
H2-Question: How much is 93 plus 76?
H2-Answer: (your answer)

Then we have to compute the answer quickly enough and pass it in H2-Answer HTTP header. If we don’t do it quickly, the response will contain the next question. Otherwise, it tells the correct answer.

sh$ curl -H 'H2-Answer: 169' -I ipsc.ksp.sk/2013/real/problems/h.html
<...>
H2: "Correct! The word you're looking for is CLASSIFICATION."

Using wget -S which prints the server response with monster message. Later setting desired headers in this way: wget "--header=Cookie: dessert=chocolate".

Check every possible gate against the five properties from http://en.wikipedia.org/wiki/Boolean_algebras_canonically_defined#Basis

You changed code incorrectly. You inserted z modulo 9 instead of z.

there must be something wrote on your code, the correct first output is "CHANGE 1607055075 TO 853225920"

We thought in exactly the same way.

I also read about it and then tried to submit "REVOLT" but it gave me a Wrong answer :D You can expect anything from a contest whose practice contest contained a Pokemon national No. :D:D

Nope you weren't :-) I thought the answer was REVOLT.

I'm sorry, that was not in English. And now my English is not good.

d1. dp[mask] — — maximal answer for permutation of letters in mask answer is final position of pointer in greedy algorithm of collecting letters from string. if dp[mask] <= n, all is OK.

d2 is interesting for me too.