参考:
http://stackoverflow.com/questions/954834/how-do-i-use-raw-input-in-python-3-1
https://docs.python.org/3/whatsnew/3.0.html
python3中 raw_input() 变成了 input()
参考:
http://stackoverflow.com/questions/954834/how-do-i-use-raw-input-in-python-3-1
https://docs.python.org/3/whatsnew/3.0.html
python3中 raw_input() 变成了 input()