\documentclass[12pt, reqno]{amsart}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\usepackage{amsthm}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage[MeX]{polski}
\usepackage[utf8]{inputenc}
\usepackage{mathrsfs}

\input cyracc.def
\font\tencyr=wncyr10
\def\cyr{\tencyr\cyracc}

\prefixing

\textwidth16cm
\headsep 10pt
\textheight22,1cm
\markboth{}{} \topmargin 0pt
\pagestyle{myheadings} \oddsidemargin 10pt \evensidemargin 10pt

\newtheorem{twi}{Twierdzenie}
\newtheorem{defi}[twi]{Definicja}
\newtheorem{wni}[twi]{Wniosek}
\newtheorem{hip}[twi]{Hipoteza}
\newtheorem{spo}[twi]{Spostrze/zenie}
\newtheorem{lem}[twi]{Lemat}
\newtheorem{prz}{Przyk/lad}
\newtheorem{uwa}{Uwaga}

\newtheorem{Thm}{Theorem}
\newtheorem{Lem}[Thm]{Lemma}
\newtheorem{Cor}[Thm]{Corollary}
\newtheorem{Pro}[Thm]{Proposition}
\newtheorem{Obs}[Thm]{Observation}
\newtheorem{Exa}[Thm]{Example}
\newtheorem{Rem}[Thm]{Remark}
\newtheorem{Def}[Thm]{Definition}

\numberwithin{equation}{section}

\DeclareMathOperator{\re}{Re}
\DeclareMathOperator{\im}{Im}
\DeclareMathOperator{\argu}{arg}

\let\Bbb=\mathbb
\let\Cal=\mathcal
\let\Mbf=\mathbf

\begin{document}

\begin{center}

{\sc\large Imi/e NAZWISKO}\vskip0.45cm

{\large \it Uczelnia {\rm(}Miasto{\rm)}}

\vskip0.45cm

{\bf\large Tytuł}

\end{center}

\vskip0.4cm

Treść (Tre/s/c). Mo/zna te/z pisa/c w Mexu.

\begin{defi}
Niech $\omega\in\mathcal{B}.$ Niech $\mathbf{D}:=\{z\in\mathbf{C}: |z|<1\}.$ 
\end{defi}

\noindent{\bf Theorem 1.} {\it Let $f: \mathbf{R}\rightarrow\mathbf{C}$ be a function of... }

\vskip0.2cm

\noindent{\bf Wniosek.} {\it  Niech $n\in \mathbf{N}.$ }

\vskip0.2cm

\noindent{\bf Uwaga.} Funkcja  $f: \mathbf{R}\rightarrow\mathbf{C}$

\begin{prz} {\rm  Niech $n\in \mathbf{N}.$ }
\end{prz}

\begin{Cor}  Let  $x\in X.$
\end{Cor}

\begin{thebibliography}{LyuTse}
\bibitem{Hal} P. R. Halmos, \emph{A Hilbert Space Problem Book}, Van Nostrand, Princeton, 1967.
\bibitem{Kan} S. Kantorovitz, \emph{Characterization of the Volterra operator and the Riemann--Liouville semigroup}, Acta Sci. Math. (Szeged) \textbf{80} (2014), 459-466.
\bibitem{Lyu} Yu. Lyubich, \emph{The power boundedness and resolvent conditions for functions of the classical Volterra operator}, Studia Math. \textbf{196} (2010), 41-63.
\bibitem{LyuTse}  Yu. Lyubich, D. Tsedenbayar, \emph{The norms and singular numbers of polynomials of the classical Volterra operator in $L_2(0,1)$}, Studia Math. \textbf{199} (2010), 171-184.
\end{thebibliography}


\end{document}
