/in/foo.cc: In function 'void dfs(int, int)':
/in/foo.cc:16:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<e[x].size();i++)
              ~^~~~~~~~~~~~
/in/foo.cc: In function 'void dfs1(int)':
/in/foo.cc:22:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<e[x].size();i++)
              ~^~~~~~~~~~~~
/in/foo.cc: In function 'void dfs2(int, int)':
/in/foo.cc:35:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<e[x].size();i++)
              ~^~~~~~~~~~~~
/in/foo.cc: In function 'int calc(int, int)':
/in/foo.cc:48:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^