/in/foo.cc: In function 'void Bubble(std::vector<Student>&)':
/in/foo.cc:22:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (i = 0; i<ary_vtStudent.size() - 1; i++)
              ~^~~~~~~~~~~~~~~~~~~~~~~~~
/in/foo.cc:25:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (j = 0; j<ary_vtStudent.size() - 1 - i; j++)
               ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/in/foo.cc: In function 'int main(int, char**)':
/in/foo.cc:57:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < ary_vtStudent.size(); i++)
                  ~~^~~~~~~~~~~~~~~~~~~~~~