/in/foo.cc: In function 'int main(int, char* const*)':
/in/foo.cc:9:2: error: 'cout' was not declared in this scope
  cout << a + b;
  ^~~~
/in/foo.cc:9:2: note: suggested alternative:
In file included from /in/foo.cc:2:0:
/usr/include/c++/6/iostream:61:18: note:   'std::cout'
   extern ostream cout;  /// Linked to standard output
                  ^~~~
/in/foo.cc:11:1: error: expected primary-expression before ')' token
 )
 ^
/in/foo.cc:11:1: error: expected '}' at end of input