blog/_posts/2018-12-07-welcome-to-jekyll.md

---
layout: post
title: Welcome to Jekyll!
subheading: hello world!
author: Jeffrey
categories: jekyll
banner: default
tags: jekyll theme yat
---

You’ll find this post in your `_posts` directory. Go ahead and edit it and re-build the site to see your changes. You can rebuild the site in many different ways, but the most common way is to run `jekyll serve`, which launches a web server and auto-regenerates your site when a file is updated.

To add new posts, simply add a file in the `_posts` directory that follows the convention `YYYY-MM-DD-name-of-post.ext` and includes the necessary front matter. Take a look at the source for this post to get an idea about how it works.

## section 1
Jekyll also offers powerful support for code snippets:

{% highlight ruby %}
def print_hi(name)
puts "Hi, #{name}"
end
print_hi('Tom')
#=> prints 'Hi, Tom' to STDOUT.
{% endhighlight %}

## section 2
### section 2.1
### section 2.2
#### section 2.2.1
##### section 2.2.1.1
#### section 2.2.2
##### section 2.2.2.1

123

## section 3
### section 3.1
### section 3.2
### section 3.3
## section 4
## section 5

Check out the [Jekyll docs][jekyll-docs] for more info on how to get the most out of Jekyll. File all bugs/feature requests at [Jekyll’s GitHub repo][jekyll-gh]. If you have questions, you can ask them on [Jekyll Talk][jekyll-talk].

[jekyll-docs]: https://jekyllrb.com/docs/home
[jekyll-gh]: https://github.com/jekyll/jekyll
[jekyll-talk]: https://talk.jekyllrb.com/

$ a * b = c ^ b $

$ 2^{\frac{n-1}{3}} $

$ \int\_a^b f(x)\,dx. $

```cpp
#include <iostream>
using namespace std;

int main() {
  cout << "Hello World!";
  return 0;
}
// prints 'Hi, Tom' to STDOUT.
```

```python
class Person:
  def __init__(self, name, age):
    self.name = name
    self.age = age

p1 = Person("John", 36)

print(p1.name)
print(p1.age)
```