For fix error with g++-4.9 :
sudo add-apt-repository ppa:ubuntu-toolchain-r/test
sudo apt-get update
sudo apt-get install g++-4.9
The Complete Guide to Setup Steem Development Environment in Ubuntu
For fix error with g++-4.9 :
sudo add-apt-repository ppa:ubuntu-toolchain-r/test
sudo apt-get update
sudo apt-get install g++-4.9