\newcommand{\arrow}{{\:\longrightarrow\:}}

\addtolength{\topmargin}{-23mm}
\addtolength{\textheight}{60mm}
\addtolength{\oddsidemargin}{-20mm}
\addtolength{\textwidth}{40mm}

\def\1{\sqrt{-1}}
\def\rad{\operatorname{\sf rad}}
\def\Alt{\operatorname{\sf Alt}}
\def\Sym{\operatorname{\sf Sym}}
\def\Id{\operatorname{\sf Id}}
\def\Hom{\operatorname{Hom}}
\def\Vol{\operatorname{Vol}}
\def\Map{\operatorname{Map}}
\newcommand{\End}{\operatorname{End}}
\newcommand{\Mat}{\operatorname{Mat}}

\def\Z{{\mathbb Z}}
\def\R{{\mathbb R}}
\def\C{{\mathbb C}}
\def\Q{{\mathbb Q}}
\def\N{{\mathbb N}}


\makeatletter
\begingroup
\gdef\th@upshape{\normalfont
  \def\@begintheorem##1##2{%
        \item[\hskip\labelsep \theorem@headerfont ##1\ ##2.]}%
\def\@opargbegintheorem##1##2##3{%
   \item[\hskip\labelsep \theorem@headerfont ##1\ ##2\ (##3).]}}
\endgroup

\theoremstyle{upshape}

\newtheorem{zadacha}{Задача}[section]
\newtheorem{opredelenie}{Определение}[section]

\begingroup
\gdef\th@upshapenonumber{\normalfont
  \def\@begintheorem##1##2{%
        \item[\hskip\labelsep \theorem@headerfont ##1.]}%
\def\@opargbegintheorem##1##2##3{%
   \item[\hskip\labelsep \theorem@headerfont ##1\ (##3).]}}
\endgroup

\theoremstyle{upshapenonumber}

\newtheorem{ukazanie}{Указание}[section]
\newtheorem{zamechanie}{Замечание}[section]

\renewcommand{\labelenumi}{\ralph{enumi}.}
\newcommand{\subs}[1]{{\bigskip \bf\large {\centerline #1}\bigskip}}
\newcommand{\sttr}{{\bf(*)}}
\newcommand{\shrk}{{\bf(!)}}
\newcommand{\doublesttr}{{\bf(**)}}

\newcommand{\listok}[2]{%
\setcounter{page}{1}
\renewcommand{\@oddhead}{\hfil #2 \hfil}
\renewcommand{\@evenhead}{\hfil #2 \hfil}
\section*{#2}
\refstepcounter{section}
\setcounter{section}{#1}
}
\makeatother



\def\бф{\bf}
\def\задача{\begin{zadacha}}
\def\ез{\end{zadacha}}
\def\замечание{\begin{zamechanie}}
\def\еза{\end{zamechanie}}
\def\указание{\begin{ukazanie}}
\def\еу{\end{ukazanie}}
\def\eu{\end{ukazanie}}
\def\определение{\begin{opredelenie}}
\def\ео{\end{opredelenie}}
\def\goth{\mathfrak}