Added 2 new training sites

Author: MTrajK

README.md

@@ -167,21 +167,23 @@ Several books that have made an impression on me:
 
 If the problems from [LeetCode](https://leetcode.com/) are not enough and you need more problems like those, you can find much more on these platforms:
 
-- [HackerRank](http://hackerrank.com/)
 - [CodeChef](http://codechef.com/)
 - [HackerEarth](http://hackerearth.com/)
 - [CodeForces](http://codeforces.com/)
 - [Topcoder](http://topcoder.com/)
-- [Project Euler](https://projecteuler.net/)
+- [AtCoder](https://atcoder.jp/)
+- [HackerRank](http://hackerrank.com/)
 - [SPOJ](http://www.spoj.com/)
 - [PEG](https://wcipeg.com/)
 - [Online Judge](https://onlinejudge.org/)
+- [AIZU OJ](https://onlinejudge.u-aizu.ac.jp/)
 - [E-Olymp](https://www.e-olymp.com/en/)
 - [VJudge](https://vjudge.net/)
 - [DMOJ](https://dmoj.ca/)
 - [USA CO](http://www.usaco.org/)
+- [POJ](http://poj.org/)
+- [Project Euler](https://projecteuler.net/)
 - [Rosetta Code](http://rosettacode.org/)
-- [AtCoder](https://atcoder.jp/)
 - [LintCode](http://www.lintcode.com/en/)
 - [Kattis](https://www.kattis.com/developers)
 - [CodeAbbey](http://codeabbey.com/)