foo.cc: In function 'void get_maxd(int, int)':
foo.cc:13:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<vec[id].size();i++)
              ~^~~~~~~~~~~~~~~
foo.cc: In function 'void get_dfn(int, int, int)':
foo.cc:27:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<vec[id].size();i++)
              ~^~~~~~~~~~~~~~~
foo.cc: In function 'void solve(int, int)':
foo.cc:42:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<vec[id].size();i++)
              ~^~~~~~~~~~~~~~~

自豪的采用jd5进行评测(github.com/masnn/jd5)