install boost on macosx

1.
$ brew install boost
==> Downloading https://homebrew.bintray.com/bottles/boost-1.57.0.yosemite.bottl
######################################################################## 100.0%
==> Pouring boost-1.57.0.yosemite.bottle.tar.gz
  /usr/local/Cellar/boost/1.57.0: 10572 files, 439M

2.  
$vi ~/.profile

BOOST_INCLUDE=/usr/local/include
export BOOST_INCLUDE

BOOST_LIB=/usr/local/lib
export BOOST_LIB

3.
source ~/.profile
4.
g++ main.cpp -I$BOOST_INCLUDE -L$BOOST_LIB