/in/foo.cc: In member function 'void primes::output()':
/in/foo.cc:23:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=2;i<xs.size();i++)
                 ~^~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:46:26: error: array must be initialized with a brace-enclosed initializer
   prime *p[i]=new prime(i);
                          ^