\documentclass{article}
\usepackage{argoclp}
\catcode`\_=\active
\def_{\_}

\def\d{{\fontencoding{T1}\selectfont\dj}}

\def\D{{\fontencoding{T1}\selectfont\DJ}}

\setlength{\textheight}{22cm} 
\newtheorem{axiom}{Aksioma}
\newtheorem{theorem}{Teorema}
\newcounter{proofstepnum} 

\begin{document}

\title{High school geometry theorems}
\author{Hilbert's axiomatic system.\\
Formalizovano od strane: Sana Stojanovic Djurdjevic \\
Dokaz generisan uz pomo\'{c}: ArgoGeoChecker.}
\date{30.03.2018.}
\maketitle

\begin{theorem}[th_1_04.]
Pod pretpostavkom da va\v{z}i $A \not \in p$ i $B \neq C$ i $B \in p$ i $C \in p$ i $\neg col(A, B, C)$ i $A \in \alpha$ i $B \in \alpha$ i $C \in \alpha$ pokazati da va\v{z}i $p \in \alpha$ i $A \in \alpha$.
\end{theorem}

{\em Dokaz:}
\setcounter{proofstepnum}{0} 


\proofstep{0} {Na osnovu \v{c}injenica $B \neq C$ i $B \in p$ i $C \in p$ i $B \in \alpha$ i $C \in \alpha$ va\v{z}i $p \in \alpha$ (aksioma $I6$).} 

\proofstep{0} {Zaklju\v{c}ak teoreme sledi iz \v{c}injenica $p \in \alpha$ i $A \in \alpha$.} 
QED
\hrule 

\end{document}
