Pip错误:需要Microsoft Visual c++ 14.0。

I just ran the "pip install -U steem"-command and the installation worked well until it failed to install pycrypto. Afterwards I did the "pip install cryptography" command because I thought it was the missing package. So my question is, how I can install steem without the pycrypto-error (or the pycrypto-package in addition) and how to deinstall the cryptography-Package which I don't need. (I'm using Windows 7 and Python 3)I just ran the "pip install -U steem"-command a