/in/foo.cc: In function 'void dfs(int)':
/in/foo.cc:118:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<tt[x].size();i++)
              ~^~~~~~~~~~~~~
/in/foo.cc:123:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<tong[x].size();i++)
              ~^~~~~~~~~~~~~~~
/in/foo.cc: In function 'int query(int, int, int, int)':
/in/foo.cc:98:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^