\documentclass[12pt,a4paper]{article}
\usepackage{theorem}
\usepackage{amssymb}
\textwidth 16cm
\textheight 25cm
\evensidemargin -.1cm
\oddsidemargin -.1cm
\topmargin -.5cm
\usepackage[polish,english]{babel}
\usepackage[cp1250]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{fancyhdr}
\pagestyle{fancy}
\renewcommand{\headrulewidth}{1pt}
\lhead{{\sf XXVIII SDM} }
\rhead{{\sf Kraków, 13 -- 16 września 2017\,r.} }
\cfoot{}
\def\affil{\date}
\def\emails#1{\toks1={#1}}

\makeatletter
\def\maketitle{%
  \null
  \setcounter{equation}{0}
  \par\vspace{.5cm}
  \begin{center}
  \leavevmode
   \large  \MakeUppercase{\@title}\\%
      \end{center}
  \begin{center}
    {  \sc \@author \par}%
    \vspace{0.1cm}
    {  \small \it \@date\par}%
 {\small \the\toks1}
  \end{center}%
 \par \vspace{-.5cm}\par
  \null
  }
\makeatother
\newenvironment{bibliogr}{\small\def\refname{ }\vspace{-1.2cm}
                        \begin{thebibliography}{9} \itemsep 0pt}
                        {\end{thebibliography}}
\setlength{\headheight}{16pt}

%--------prosimy nie edytować pliku powyżej tej linii------------------
%-------------nowe środowiska i polecenia------------------------------




%---------------dane referatu------------------------------------------
\title{tytuł referatu}
\author{Autor}
\affil{Afiliacja} %common  affiliation of authors1,2
%\author[2]{Firstname Lastname}
%\affil[2]{University, Country}%affiliation different from above
\emails{example@poczta.pl}%put authors' email addresses here


\begin{document}
\maketitle


%-----------------------Tekst abstraktu--------------------------------


Tekst abstraktu Tekst abstraktu Tekst abstraktu Tekst abstraktu Tekst abstraktu Tekst abstraktu Tekst abstraktu Tekst abstraktu Tekst abstraktu Tekst abstraktu Tekst abstraktu


%--------------------literatura (opcjonalnie)--------------------------


\begin{bibliogr}
\bibitem{1}
F.~Lastname,  \textit{title of the paper}, Journal Abbreviation. {\bf 2} (2016), 55–-56.
\bibitem{2}
 F.~Lastname,  \textit{title of the book},
Serie Name, {\bf 2}, Publisher, Place of publishing, 2016.
\end{bibliogr}


\end{document}
