/// \brief Dimacs file format reader.

 /// \brief DIMACS file format reader.

   /// Dimacs min cost flow reader function.

   /// DIMACS min cost flow reader function.

   ///

   /// This function reads a min cost flow instance from dimacs format,

   /// This function reads a min cost flow instance from DIMACS format,

   /// i.e. from dimacs files having a line starting with

   /// i.e. from DIMACS files having a line starting with

   ///\code

   /// \code

   /// p "min"

   ///   p min

   ///\endcode

   /// \endcode

   /// At the beginning \c g is cleared by \c g.clear(). The edge

   /// At the beginning \c g is cleared by \c g.clear(). The supply 

   /// capacities are written to \c capacity, \c s and \c t are set to

   /// amount of the nodes are written to \c supply (signed). The 

   /// the source and the target nodes resp. and the cost of the edges

   /// lower bounds, capacities and costs of the edges are written to 

   /// are written to \c cost.

   /// \c lower, \c capacity and \c cost.

   ///

   ///

   /// \author Marton Makai

   /// \author Marton Makai and Peter Kovacs

   template<typename Graph, typename CapacityMap, typename CostMap>

   template <typename Graph, typename SupplyMap, 

   void readDimacs(std::istream& is, Graph &g, CapacityMap& capacity, 

     typename CapacityMap, typename CostMap>

 		  typename Graph::Node &s, typename Graph::Node &t, 

   void readDimacs( std::istream& is,

 		  CostMap& cost) {

 		   Graph &g,

 		   SupplyMap& supply, 

 		   CapacityMap& lower, 

 		   CapacityMap& capacity, 

 		   CostMap& cost )

   {

     typename CapacityMap::Value _cap;

     std::vector<typename Graph::Node> nodes;

     typename CostMap::Value _cost;

     typename Graph::Edge e;

     char d;

     std::string problem, str;

     std::string problem;

     std::string str;

     typename SupplyMap::Value sup;

     int n, m; 

     typename CapacityMap::Value low;

     typename Graph::Edge e;

     typename CapacityMap::Value cap;

     std::vector<typename Graph::Node> nodes;

     typename CostMap::Value co;

     while (is>>c) {

     while (is >> c) {

       case 'c': //comment

       case 'c': // comment line

 	getline(is, str);

 	getline(is, str);

 	break;

 	break;

       case 'p': //problem definition

       case 'p': // problem definition line

 	nodes.resize(n+1);

 	if (problem != "min") return;

 	for (int k=1; k<=n; ++k) nodes[k]=g.addNode();

 	nodes.resize(n + 1);

 	break;

 	for (int k = 1; k <= n; ++k) {

       case 'n': //node definition

 	  nodes[k] = g.addNode();

 	if (problem=="sp") { //shortest path problem

 	  supply[nodes[k]] = 0;

 	  is >> i;

 	}

 	  getline(is, str);

 	break;

 	  s=nodes[i];

       case 'n': // node definition line

 	}

 	is >> i >> sup;

 	if (problem=="max" || problem=="min") { //((max) or (min cost)) flow problem

 	getline(is, str);

 	  is >> i >> d;

 	supply.set(nodes[i], sup);

 	  getline(is, str);

 	break;

 	  if (d=='s') s=nodes[i];

       case 'a': // edge (arc) definition line

 	  if (d=='t') t=nodes[i];

 	is >> i >> j >> low >> cap >> co;

 	}

 	getline(is, str);

 	break;

 	e = g.addEdge(nodes[i], nodes[j]);

       case 'a':

 	lower.set(e, low);

 	if ( problem == "max" || problem == "sp") {

 	if (cap >= 0)

 	  is >> i >> j >> _cap;

 	  capacity.set(e, cap);

 	  getline(is, str);

 	else

 	  e=g.addEdge(nodes[i], nodes[j]);

 	  capacity.set(e, -1);

 	  //capacity.update();

 	cost.set(e, co);

 	  capacity.set(e, _cap);

 	} else {

 	  if ( problem == "min" ) {

 	    is >> i >> j >> _cap >> _cost;

 	    getline(is, str);

 	    e=g.addEdge(nodes[i], nodes[j]);

 	    //capacity.update();

 	    capacity.set(e, _cap);

 	    //cost.update();

 	    cost.set(e, _cost);

 	  } else {

 	    is >> i >> j;

 	    getline(is, str);

 	    g.addEdge(nodes[i], nodes[j]);

 	  }

 	}

   /// DIMACS max flow reader function.

   /// Dimacs max flow reader function.

   ///

   /// This function reads a max flow instance from DIMACS format,

   /// This function reads a max flow instance from dimacs format,

   /// i.e. from DIMACS files having a line starting with

   /// i.e. from dimacs files having a line starting with

   /// \code

   ///\code

   ///   p max

   /// p "max"

   /// \endcode

   ///\endcode

   /// At the beginning \c g is cleared by \c g.clear(). The edge 

   ///At the beginning \c g is cleared by \c g.clear(). The

   /// capacities are written to \c capacity and \c s and \c t are

   /// edge capacities are written to \c capacity and \c s and \c t are

     NullMap<typename Graph::Edge, int> n;

     g.clear();

     readDimacs(is, g, capacity, s, t, n);

     std::vector<typename Graph::Node> nodes;

   }

     typename Graph::Edge e;

     std::string problem;

     char c, d;

   /// Dimacs shortest path reader function.

     int n, m; 

     int i, j;

   /// This function reads a shortest path instance from dimacs format,

     typename CapacityMap::Value _cap;

   /// i.e. from dimacs files having a line starting with

     std::string str;

   ///\code

     while (is >> c) {

   /// p "sp"

       switch (c) {

   ///\endcode

       case 'c': // comment line

 	getline(is, str);

 	break;

       case 'p': // problem definition line

 	is >> problem >> n >> m;

 	getline(is, str);

 	nodes.resize(n + 1);

 	for (int k = 1; k <= n; ++k)

 	  nodes[k] = g.addNode();

 	break;

       case 'n': // node definition line

 	if (problem == "sp") { // shortest path problem

 	  is >> i;

 	  getline(is, str);

 	  s = nodes[i];

 	}

 	if (problem == "max") { // max flow problem

 	  is >> i >> d;

 	  getline(is, str);

 	  if (d == 's') s = nodes[i];

 	  if (d == 't') t = nodes[i];

 	}

 	break;

       case 'a': // edge (arc) definition line

 	if (problem == "max" || problem == "sp") {

 	  is >> i >> j >> _cap;

 	  getline(is, str);

 	  e = g.addEdge(nodes[i], nodes[j]);

 	  capacity.set(e, _cap);

 	} else {

 	  is >> i >> j;

 	  getline(is, str);

 	  g.addEdge(nodes[i], nodes[j]);

 	}

 	break;

       }

     }

   }

   /// DIMACS shortest path reader function.

   ///

   /// This function reads a shortest path instance from DIMACS format,

   /// i.e. from DIMACS files having a line starting with

   /// \code

   ///   p sp

   /// \endcode

     NullMap<typename Graph::Edge, int> n;

     readDimacs(is, g, capacity, s, s);

     readDimacs(is, g, capacity, s, s, n);

   }

   }

   /// DIMACS capacitated graph reader function.

   ///

   /// Dimacs capacitated graph reader function.

   /// dimacs format.  At the beginning \c g is cleared by \c g.clear()

   /// DIMACS format. At the beginning \c g is cleared by \c g.clear()

     NullMap<typename Graph::Edge, int> n;

     readDimacs(is, g, capacity, u, u);

     readDimacs(is, g, capacity, u, u, n);

   }

   }

   /// DIMACS plain graph reader function.

   ///

   /// Dimacs plain graph reader function.

   /// maps from dimacs format, i.e. from dimacs files having a line

   /// maps from DIMACS format, i.e. from DIMACS files having a line

   ///\code

   /// \code

   /// p "mat"

   ///   p mat

   ///\endcode

   /// \endcode

   /// At the beginning \c g is cleared

   /// At the beginning \c g is cleared by \c g.clear().

   /// by \c g.clear().

     readDimacs(is, g, n, u, u, n);

     readDimacs(is, g, n, u, u);

   /// DIMACS plain graph writer function.

   ///

   /// This function writes a graph without any designated nodes and

   /// write matching problem

   /// maps into DIMACS format, i.e. into DIMACS file having a line 

   /// starting with

   /// \code

   ///   p mat

   /// \endcode

   ///

   /// \author Marton Makai

     int i = 1;

     os << "c matching problem" << std::endl;

     for(NodeIt v(g); v != INVALID; ++v) {

     int i=1;

     for(NodeIt v(g); v!=INVALID; ++v) {

     for(EdgeIt e(g); e != INVALID; ++e) {

     os << "p mat " << g.nodeNum() << " " << g.edgeNum() << std::endl;

     for(EdgeIt e(g); e!=INVALID; ++e) {