/in/foo.cc:79:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main()
      ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:109:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(int j=0;j<ha[x].size();j++){
                ~^~~~~~~~~~~~~
/in/foo.cc:89:13: warning: 'rt' may be used uninitialized in this function [-Wmaybe-uninitialized]
  dfs2(rt,rt);
             ^