/in/foo.cc: In function 'void dts::clear()':
/in/foo.cc:24:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i=0;i<e.size();i++)
                ~^~~~~~~~~
/in/foo.cc: In function 'int dts::bfs()':
/in/foo.cc:40:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for (int i=0;i<e[now].size();i++)
                 ~^~~~~~~~~~~~~~