In file included from main.cpp:55:0:
visitor.h:16:37: error: two or more data types in declaration of 'type name'
   std::map<int, std::pair<int, int> Vert;
                                     ^~~~
visitor.h:16:37: error: template argument 2 is invalid
visitor.h:16:37: error: template argument 4 is invalid
visitor.h: In instantiation of 'size_t BfsVisitor<Vertex>::DistanceTo(const Vertex&) const [with Vertex = int; size_t = long unsigned int]':
main.cpp:65:29:   required from here
visitor.h:48:15: error: invalid use of 'BfsVisitor<int>::Vert::Vert'
   return vrt->Vert[trg].second;
          ~~~~~^~~~
visitor.h: In instantiation of 'Vertex BfsVisitor<Vertex>::Parent(const Vertex&) const [with Vertex = int]':
main.cpp:68:25:   required from here
visitor.h:51:53: error: invalid use of 'BfsVisitor<int>::Vert::Vert'
 Vertex Parent(const Vertex &vr) const { return vrt->Vert[vr].first; }
                                                ~~~~~^~~~
visitor.h: In instantiation of 'void BfsVisitor<Vertex>::DiscoverVertex(const Vertex&) [with Vertex = int]':
main.cpp:13:3:   required from 'void BreadthFirstSearch(const Graph&, const Vertex&, Visitor) [with Graph = UndirectedGraph<int>; Vertex = int; Visitor = BfsVisitor<int>]'
main.cpp:64:41:   required from here
visitor.h:36:10: error: invalid use of 'BfsVisitor<int>::Vert::Vert'
     vrt->Vert.insert(std::make_pair(0, std::make_pair(0, 0)));
     ~~~~~^~~~
visitor.h:37:19: error: invalid use of 'BfsVisitor<int>::Vert::Vert'
   } else if (vrt->Vert.find(vr) != vrt->Vert.end()) {
              ~~~~~^~~~
visitor.h:37:41: error: invalid use of 'BfsVisitor<int>::Vert::Vert'
   } else if (vrt->Vert.find(vr) != vrt->Vert.end()) {
                                    ~~~~~^~~~
visitor.h:38:25: error: invalid use of 'BfsVisitor<int>::Vert::Vert'
       if (vrt->b < vrt->Vert[vr].second) {
                    ~~~~~^~~~
visitor.h:39:14: error: invalid use of 'BfsVisitor<int>::Vert::Vert'
         vrt->Vert[vr].first = vrt->a;
         ~~~~~^~~~
visitor.h:40:14: error: invalid use of 'BfsVisitor<int>::Vert::Vert'
         vrt->Vert[vr].second = vrt->b;
         ~~~~~^~~~
visitor.h:43:14: error: invalid use of 'BfsVisitor<int>::Vert::Vert'
         vrt->Vert.insert(std::make_pair(vr, std::make_pair(vrt->a, vrt->b)));
         ~~~~~^~~~
visitor.h: In instantiation of 'void BfsVisitor<Vertex>::ExamineVertex(const Vertex&) [with Vertex = int]':
main.cpp:18:5:   required from 'void BreadthFirstSearch(const Graph&, const Vertex&, Visitor) [with Graph = UndirectedGraph<int>; Vertex = int; Visitor = BfsVisitor<int>]'
main.cpp:64:41:   required from here
visitor.h:31:17: error: invalid use of 'BfsVisitor<int>::Vert::Vert'
   vrt->b = vrt->Vert[vr].second + 1;
            ~~~~~^~~~