/in/foo.cc: In function 'void dfs(int)':
/in/foo.cc:15:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<vec[rt].size();i++){
              ~^~~~~~~~~~~~~~~
/in/foo.cc:13:20: warning: variable 'loc' set but not used [-Wunused-but-set-variable]
  int ch=2147483647,loc,bo;
                    ^~~