#include<lemon/lp_glpk.h>

 #include<lemon/graph_reader.h>

 #include<lemon/list_graph.h>

 using namespace lemon;

 template<class G,class C>

 double maxFlow(const G &g,const C &cap,typename G::Node s,typename G::Node t)

 {

   LpGlpk lp;

   typedef G Graph;

   typedef typename G::Node Node;

   typedef typename G::NodeIt NodeIt;

   typedef typename G::Edge Edge;

   typedef typename G::EdgeIt EdgeIt;

   typedef typename G::OutEdgeIt OutEdgeIt;

   typedef typename G::InEdgeIt InEdgeIt;

   typename G::template EdgeMap<LpGlpk::Col> x(g);

   lp.addColSet(x);

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

     lp.colUpperBound(x[e],cap[e]);

     lp.colLowerBound(x[e],0);

   }

   for(NodeIt n(g);n!=INVALID;++n) if(n!=s&&n!=t) {

     LpGlpk::Expr ex;

     for(InEdgeIt  e(g,n);e!=INVALID;++e) ex+=x[e];

     for(OutEdgeIt e(g,n);e!=INVALID;++e) ex-=x[e];

     lp.addRow(ex==0);

   }

   {

     LpGlpk::Expr ex;

     for(InEdgeIt  e(g,t);e!=INVALID;++e) ex+=x[e];

     for(OutEdgeIt e(g,t);e!=INVALID;++e) ex-=x[e];

     lp.setObj(ex);

   }

   lp.max();

   lp.presolver(true);

   lp.messageLevel(3);

   lp.solve();

   return lp.primalValue();

 }

 int main() 

 {

   ListGraph g;

   ListGraph::Node s;

   ListGraph::Node t;

   ListGraph::EdgeMap<double> cap(g);

   GraphReader<ListGraph> reader(std::cin,g);

   reader.addNode("source",s).addNode("target",t)

     .addEdgeMap("capacity",cap).run();

   // std::ifstream file("../test/preflow_");

 //   readDimacs(file, g, cap, s, t);

   std::cout << "Max flow value = " << maxFlow(g,cap,s,t) << std::endl;

 }