Problems with GCC

Hello freedom defenders! After running "Software & Updates", I had a problem compiling C++ programs: /usr/lib/x86_64-linux-gnu/libstdc++.so.6: version `GLIBCXX_3.4.21' not found

It's a linking problem...
Then I solved it linking statically: g++ -o blitz blitz.cpp -static
This "solved" the problem, but it is not the best solution.

I'm using GCC 6.3

Thanks for reading!