/in/foo.cc: In function 'void dts::dfs(std::vector<double>)':
/in/foo.cc:35:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for (ll i=0;i<rec.size();i++)
                         ~^~~~~~~~~~~
/in/foo.cc:36:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
                 for (ll j=i+1;j<rec.size();j++)
                               ~^~~~~~~~~~~
/in/foo.cc:38:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
                     for (ll k=0,l=0;k<rec.size();k++)
                                     ~^~~~~~~~~~~