\chapter*{Preface} \markboth{\MakeUppercase{Preface}}{} \addcontentsline{toc}{chapter}{Preface} The purpose of this book is to give you a thorough introduction to competitive programming. The book assumes that you already know the basics of programming, but previous background on competitive programming is not needed. The book is especially intended for high school students who want to learn algorithms and possibly participate in the International Olympiad in Informatics (IOI). The book is also suitable for university students and anybody else interested in competitive programming. It takes a long time to become a good competitive programmer, but it is also an opportunity to learn a lot. You can be sure that you will learn a great deal about algorithms if you spend time reading the book and solving exercises. The book is under continuous development. You can always send feedback about the book to \texttt{ahslaaks@cs.helsinki.fi}.