/in/foo.cc: In function 'int main()':
/in/foo.cc:28:30: error: variable 'std::stringstream ss' has initializer but incomplete type
         stringstream ss(input);
                              ^
/in/foo.cc:34:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < dates.size(); i++) {
                       ^