problem

PS C:\Users\sanav> gem install rails
Fetching: i18n-0.6.4.gem (100%)
Successfully installed i18n-0.6.4
Fetching: tzinfo-0.3.37.gem (100%)
Successfully installed tzinfo-0.3.37
Fetching: atomic-1.1.12.gem (100%)
Temporarily enhancing PATH to include DevKit...
Building native extensions.  This could take a while...
ERROR:  Error installing rails:
        ERROR: Failed to build gem native extension.

    C:/Ruby200-x64/bin/ruby.exe extconf.rb
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
        --with-opt-dir
        --without-opt-dir
        --with-opt-include
        --without-opt-include=${opt-dir}/include
        --with-opt-lib
        --without-opt-lib=${opt-dir}/lib
        --with-make-prog
        --without-make-prog
        --srcdir=.
        --curdir
        --ruby=C:/Ruby200-x64/bin/ruby
        --with-atomic_reference-dir
        --without-atomic_reference-dir
        --with-atomic_reference-include
        --without-atomic_reference-include=${atomic_reference-dir}/include
        --with-atomic_reference-lib
        --without-atomic_reference-lib=${atomic_reference-dir}/