/in/foo.cc: In function 'int dfs1(int, int, int)':
/in/foo.cc:19:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < g[rt].size(); i++) {
                  ~~^~~~~~~~~~~~~~
/in/foo.cc: In function 'void dfs2(int)':
/in/foo.cc:32:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < g[rt].size(); i++) {
                  ~~^~~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:55:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j = 0; j < dep_sum_index[i].size(); j++) {
                   ~~^~~~~~~~~~~~~~~~~~~~~~~~~