/in/foo.cc: In function 'void dfs(int)':
/in/foo.cc:27:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < edge[p].size(); i++)
                  ~~^~~~~~~~~~~~~~~~
/in/foo.cc: In function 'void work(int)':
/in/foo.cc:59:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < X[p].size(); i++)
                  ~~^~~~~~~~~~~~~
/in/foo.cc:64:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < edge[p].size(); i++)
                  ~~^~~~~~~~~~~~~~~~