\documentclass[]{article}
\usepackage[T1]{fontenc}
\usepackage{polski}
\usepackage[utf8]{inputenc}
\usepackage[margin=1.25in]{geometry}
\usepackage{alltt}
\usepackage{titling}
\usepackage{pdfpages}
\usepackage{float}
\usepackage{amsmath}
\usepackage{booktabs}
\usepackage{tabularx}
\usepackage{amstext}
\usepackage{tikz}
\usepackage{xspace}
\usepackage{enumerate}
\usepackage{lmodern}
\usepackage{amsfonts}
\usepackage{mathtools}
\usepackage{alphalph}
\usepackage{algorithm}
\usepackage{algpseudocode}

\DeclarePairedDelimiter\ceil{\lceil}{\rceil}
\DeclarePairedDelimiter\floor{\lfloor}{\rfloor}

\usetikzlibrary{decorations.pathmorphing, arrows.meta, positioning}
\usetikzlibrary{shapes.geometric, arrows}

\tikzstyle{problem} = [draw,outer sep=0,inner sep=5,minimum size=10]
\tikzstyle{solution} = [outer sep=0,inner sep=1,minimum size=10]
\tikzstyle{alpha} = [decorate, decoration={snake, amplitude=.5mm}, help lines] 
\tikzstyle{max edge} = [very thick, blue]
\tikzstyle{vertex} = [draw, circle, thick]
\tikzstyle{small vertex} = [draw, circle, scale=.75]
\tikzstyle{weight} = [scale=.75, fill=white, draw]

\pgfdeclarelayer{background}
\pgfdeclarelayer{foreground}
\pgfsetlayers{background,main,foreground}

% opening
\title{PAA - Kolokwia, rozwiązania}
\author{Kacper Donat}

\newcounter{task}[section]
\newcounter{subtask}[task]
\newcounter{tip}[task]

\renewcommand{\thesubtask}{\alph{subtask}}

\newcommand{\NP}{\texttt{NP}\xspace}
\newcommand{\NPC}{\texttt{NPC}\xspace}
\newcommand{\NPI}{\texttt{NPI}\xspace}
\renewcommand{\P}{\texttt{P}\xspace}

\newcommand{\problem}[1]{\texttt{#1}}

\newcommand{\taskend}{\par\vspace{.1cm}\hfill$\square$\vspace{.4cm}\par}
\newcommand{\task}{\vspace{.25cm}\refstepcounter{task} \noindent\par\texttt{Zadanie \thesection.\thetask.\hspace{.1cm}}}
\newcommand{\subtask}[1][]{\refstepcounter{subtask}\par\noindent\hspace{.3cm}\thesubtask#1)\ }

\newcommand{\solution}{\par\vspace{.5cm}\noindent\textbf{Proponowane rozwiązanie:}\par}
\newcommand{\tip}[1]{\par\noindent\textit{Wskazówka:} #1\par}
\newcommand{\ctip}[1]{\refstepcounter{tip}\par\noindent\textit{Wskazówka \#\thetip:} #1\par}

\newenvironment{shortcut}{\vspace{.4cm}\noindent\textbf{Na skróty:}\vspace{2mm}\hline\vspace{.4cm}}{\vspace{.4cm}\hline\vspace{.4cm}}
\newenvironment{column}[1]{\begin{minipage}{#1\linewidth}}{\end{minipage}\vspace{.5\baselineskip}}

\begin{document}

\input{./2013.01.26.tex}
\input{./2011.01.18.tex}

\end{document}