foo.cc: In function ‘void dts::main()’:
foo.cc:85:23: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<dts::posi>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   85 |         for (int i=0;i<a.size();i++)
      |                      ~^~~~~~~~~
foo.cc:97:23: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<dts::edge>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   97 |         for (int i=1;i<e.size();i++)
      |                      ~^~~~~~~~~