Hello everyone! I've written a script in emacs lisp, that can:

• Submit solution
• Download tests
• Enter by handle/password
• Store cookies between runs

All the requests are made using curl. link.

Installation

• Download script.
• Insert to your ~/.emacs file the following code:

(add-to-list 'load-path "/folder/containing/script/")
(load "cf-keys.el")

Using

• C-c i — Log in
• C-c o — Log out
• C-c w — Get your current handle
• C-c s — Submit currently open file
• C-c d — Save tests to current folder

Submit and save functions "guess" the contest number, problem index and the programming language by the current file name in one of the following forms:

• directory/505/A/myfile.cpp
• directory/505/a.c
• directory/505a.cc

Setup

In your ~/.emacs file you can change the default variable values:

• cf-default-language — Default language. Can be one of the values defined in cf-languages.el
• cf-host — "codeforces.ru" or "codeforces.com"
• cf-cookies-file — File, in which curl will store cookies

Example: (setq cf-cookies-file "/home/vasya/my_codeforces_cookies")

Keybindings can be changed at the end of the file cf-keys.el.

What is probability to guess the answer of this problem?

A. 25%
B. 50%
C. 60%
D. 25%

I found another variants of this problem:link , translated