Euler's totient function, also known as **phi-function** $\phi (n)$, counts the number of integers between 1 and $n$ inclusive, which are coprime to $n$. Two numbers are coprime if their greatest common divisor equals $1$ ($1$ is considered to be coprime to any number).

<iframe width="420" height="315" src="https://www.youtube.com/embed/TrBBw4J9X30" frameborder="0" allowfullscreen></iframe>

</div>

Some contributors add explicit links to their profiles at the bottom of the translated articles. However it is discouraged and simply not very convenient if the article was edited by several people. Every page has `Page Authors` link in its top - this link leads to the github commit history, so it is always easy to determine or prove the authorship (even of any single line). Just make sure that your GitHub profile (which is mentioned in history) provides enough information about you.

We use [Markdown](https://daringfireball.net/projects/markdown) for source texts and

convert them automatically to HTML.

* We have agreed as of issue [#83](https://github.com/e-maxx-eng/e-maxx-eng/issues/83) to express binomial coefficients with `\binom{n}{k}` instead of `C_n^k`. The first one renders as $\binom{n}{k}$ and is a more universal convention. The second would render as $C_n^k$.

Small images could be pushed along with texts to the [/img](https://github.com/e-maxx-eng/e-maxx-eng/tree/master/img) subfolder. Let them be in `PNG` format and less than `200kb`. Then you can refer to them inside the article with the tag:

For more detail read the [Implementation](#implementation).

More infos in [Impl. of Segmenttree](./data_structures/segment_tree.html#implementation).

Template for the pages (the one which creates small violet header and footer, determines the layout of the text, includes css and js files) is now also stored in this repo, in [src/\_templates](https://github.com/e-maxx-eng/e-maxx-eng/tree/master/src/_templates) folder. So in case you find some bugs in it, or with the passing of time some new features may be needed in it - create PR to improve it. Note that for testing purposes the alternative template could be created and used for specific page with the inclusion of special comment as shown below:

_You can [see the source of this article](https://raw.githubusercontent.com/e-maxx-eng/e-maxx-eng/master/src/demo-article.md) to better understand formatting features._

return result;

}

We use [Markdown](https://daringfireball.net/projects/markdown) for source texts and

convert them automatically to HTML.

Small images could be pushed along with texts to the [/img](https://github.com/e-maxx-eng/e-maxx-eng/tree/master/img) subfolder. Let them be in `PNG` format and less than `200kb`. Then you can refer to them inside the article like this (see the source here):

Divide and Conquer is a dynamic programming optimization.

You are given a directed graph $G$ with vertices $V$ and edges $E$. It is possible that there are loops and multiple edges. Let's denote $n$ as number of vertices and $m$ as number of edges in $G$.