foo.cc: In function ‘void dts::tr_dfs1(ll, ll)’:
foo.cc:29:22: warning: comparison of integer expressions of different signedness: ‘dts::ll’ {aka ‘long long int’} and ‘std::vector<long long int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   29 |         for (ll i=0;i<tr[now].s.size();i++)
      |                     ~^~~~~~~~~~~~~~~~~
foo.cc: In function ‘void dts::tr_dfs2(ll)’:
foo.cc:41:22: warning: comparison of integer expressions of different signedness: ‘dts::ll’ {aka ‘long long int’} and ‘std::vector<long long int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   41 |         for (ll i=0;i<tr[now].s.size();i++)
      |                     ~^~~~~~~~~~~~~~~~~