/in/foo.cc: In function 'void Dijskra_Forward()':
/in/foo.cc:39:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < E[now].size(); ++i) {
                   ~~^~~~~~~~~~~~~~~
/in/foo.cc: In function 'void Dijskra_Reverse()':
/in/foo.cc:63:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < ER[now].size(); ++i) {
                   ~~^~~~~~~~~~~~~~~~