/in/foo.cc: In function 'void pushback_sthgroup(int, int, int, int)':
/in/foo.cc:15:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<node_external::node_internal>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   15 |         for(int i=0;i<sth_group[affiliated].each_sth.size();i++){
      |                     ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~