Julyed felt so bored that she began to write numbers on the coordinate paper. She wrote a “0” on the center, then wrote the follow numbers clockwise, which looked like a snake as below.
![技术分享](http://exam.upc.edu.cn/upload/image/20160608/20160608215518_66811.png)
Julyed was looking at paper. Suddenly, she began to feel curious.
“What is the nth number on the positive axis of Y axis?”
She asked tomriddly for the question. But tomriddly was so busy that he ignored Julyed. So now you have to solve this problem.