/in/foo.cc: In function 'void dfs(int)':
/in/foo.cc:24:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int v, i = 0; i < g[u].size(); ++i)
                     ~~^~~~~~~~~~~~~
/in/foo.cc: In function 'void dfs(int, int)':
/in/foo.cc:33:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int v, i = 0; i < g[u].size(); ++i) {
                     ~~^~~~~~~~~~~~~
/in/foo.cc: In function 'void dfs1(int, int)':
/in/foo.cc:44:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int v, i = 0; i < g[u].size(); ++i)
                     ~~^~~~~~~~~~~~~
/in/foo.cc:46:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < stag[u].size(); ++i) ++b1[stag[u][i]+N];
                  ~~^~~~~~~~~~~~~~~~
/in/foo.cc:48:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < snetag[u].size(); ++i) --b1[snetag[u][i]+N];
                  ~~^~~~~~~~~~~~~~~~~~
/in/foo.cc: In function 'void dfs2(int, int)':
/in/foo.cc:52:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int v, i = 0; i < g[u].size(); ++i)
                     ~~^~~~~~~~~~~~~
/in/foo.cc:54:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < ttag[u].size(); ++i) ++b2[ttag[u][i]+N];
                  ~~^~~~~~~~~~~~~~~~
/in/foo.cc:56:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < tnetag[u].size(); ++i) --b2[tnetag[u][i]+N];
                  ~~^~~~~~~~~~~~~~~~~~