/in/foo.cc: In function 'void dts::main()':
/in/foo.cc:49:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (ll i=stk.back().i;i<e[stk.back().x].size();i++,stk.back().i=i)
                            ~^~~~~~~~~~~~~~~~~~~~~~~
/in/foo.cc:67:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     if (stk.back().i>=e[stk.back().x].size())
         ~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~