Can't install Rails on Ubuntu 16.04

i'm noob. This is my problem when i try.

Building native extensions. This could take a while... ERROR: Error installing rails: ERROR: Failed to build gem native extension.

current directory: /var/lib/gems/2.3.0/gems/nio4r-1.2.1/ext/nio4r

/usr/bin/ruby2.3 -r ./siteconf20160630-19108-12sbtb7.rb extconf.rb mkmf.rb can't find header files for ruby at /usr/lib/ruby/include/ruby.h

extconf failed, exit code 1

Gem files will remain installed in /var/lib/gems/2.3.0/gems/nio4r-1.2.1 for inspection. Results logged to /var/lib/gems/2.3.0/extensions/x86-linux/2.3.0/nio4r-1.2.1/gem_make.out

I needed to install ruby-dev:

sudo apt-get install ruby-dev zlib1g-dev liblzma-dev

Cf: This question on StackOverflow. It recommends sudo apt-get install build-essential patch first, but my system didn't need that.