/in/foo.cc: In function 'void dfs(int, int, int)':
/in/foo.cc:27:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i=0;i<g[x].size();i++) {
               ~^~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:61:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i=0;i<g[1].size();i++) {
               ~^~~~~~~~~~~~