In file included from /in/driver/main.cpp:8:0:
/in/kdtree.hpp: In constructor 'KDTree<std::tuple<_Elements ...>, ValueType>::KDTree(std::vector<std::pair<std::tuple<_Elements ...>, ValueType> >)':
/in/kdtree.hpp:472:13: error: 'v' was not declared in this scope
         if (v.empty())
             ^
/in/kdtree.hpp:476:26: error: 'v' was not declared in this scope
         std::stable_sort(v.begin(), v.end());
                          ^
/in/kdtree.hpp: In instantiation of 'KDTree<std::tuple<_Elements ...>, ValueType>::KDTree(std::vector<std::pair<std::tuple<_Elements ...>, ValueType> >) [with ValueType = std::__cxx11::basic_string<char>; KeyTypes = {int, int, int}]':
/in/driver/main.cpp:43:57:   required from here
/in/kdtree.hpp:470:56: error: unused parameter 'elements' [-Werror=unused-parameter]
     explicit KDTree(std::vector<std::pair<Key, Value>> elements) {
                                                        ^~~~~~~~
cc1plus: all warnings being treated as errors