/in/foo.cc: In function 'int main()':
/in/foo.cc:13:9: error: 'cont' was not declared in this scope
         cont << endl; 
         ^~~~
/in/foo.cc:20:34: error: no match for 'operator*' (operand types are 'std::__cxx11::string {aka std::__cxx11::basic_string<char>}' and 'int')
   cout << "快递费为：" << a * 5;
                                ~~^~~