#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <map>
#include <vector>
#include <string>
using namespace std;

class Node {
  public: 
    string name;
    vector <class Edge *> adj;
    int visited;
};

class Edge {
  public:
    string name;
    Node *n1;
    Node *n2;
    Edge *reverse;
    double original;
    double residual;
    double flow;
};

class Graph {
  public:
     Graph();
     ~Graph();
     void Print();
     Node *Get_Node(string &s);
     Edge *Get_Edge(Node *n1, Node *n2);
  
     double Find_Max_Flow();
     double Find_Augmenting_Path();
     int DFS(Node *n);

     Node *Source;
     Node *Sink;
     vector <Node *> Nodes; 
     vector <Edge *> Edges; 
     map <string, Node *> N_Map;
     map <string, Edge *> E_Map;
};

double Graph::Find_Max_Flow()
{
  double total;
  double f;
  Edge *e;
  int i;

  for (i = 0; i < Edges.size(); i++) {
    e = Edges[i];
    e->flow = 0;
    e->residual = e->original;
  }
  total = 0;
  while (1) {
    f = Find_Augmenting_Path();
    if (f == 0) {
      return total;
    } else {
      total += f;
    }
  }
}

double Graph::Find_Augmenting_Path()
{
  int i;

  for (i = 0; i < Nodes.size(); i++) Nodes[i]->visited = 0;
  if (DFS(Source)) {
    printf("Quitting.\n");
  }
  exit(0);
}

int Graph::DFS(Node *n)
{
  int i;
  Edge *e;
  double f;

  if (n->visited) return 0;
  n->visited = 1;
  if (n == Sink) return 1;

  for (i = 0; i < n->adj.size(); i++) {
    e = n->adj[i];
    if (e->residual > 0) {
      if (DFS(e->n2)) {
        printf("Found a path to the sink.  Edge %s.\n", e->name.c_str());
        return 1;
      }
    }
  }
  return 0;
}
  
void Graph::Print()
{
  Node *n;
  Edge *e;
  int i, j;

  printf("Source: %s\n", Source->name.c_str());
  printf("Sink:   %s\n", Sink->name.c_str());

  for (i = 0; i < Nodes.size(); i++) {
    n = Nodes[i];
    printf("Node %s:", n->name.c_str());
    for (j = 0; j < n->adj.size(); j++) {
      e = n->adj[j];
      printf(" (%s:%.3lf)", e->name.c_str(), e->original);
    }
    printf("\n");
  }
}

Graph::Graph()
{
  string s, f, t;
  double cap;
  Node *n1, *n2;
  Edge *e;

  Source = NULL;
  Sink = NULL;

  while (cin >> s) {
    if (s == "SOURCE") {
      cin >> s;
      if (Source != NULL) { fprintf(stderr, "Can't specify two sources\n"); exit(1); }
      Source = Get_Node(s);
    } else if (s == "SINK") {
      cin >> s;
      if (Sink != NULL) { fprintf(stderr, "Can't specify two sinks\n"); exit(1); }
      Sink = Get_Node(s);
    } else if (s == "EDGE") {
      cin >> f >> t >> cap;


      n1 = Get_Node(f);
      n2 = Get_Node(t);

      e = Get_Edge(n1, n2);
      e->original += cap;

      if (e->reverse == NULL) {
        e->reverse = Get_Edge(n2, n1);
        e->reverse->reverse = e;
        n1->adj.push_back(e);
        n2->adj.push_back(e->reverse);
      }
    }
  }

  if (Source == NULL) { fprintf(stderr, "No Source.\n"); exit(1); }
  if (Sink == NULL) { fprintf(stderr, "No Sink.\n"); exit(1); }
}

Graph::~Graph()
{
  int i;

  for (i = 0; i < Nodes.size(); i++) delete(Nodes[i]);
  for (i = 0; i < Edges.size(); i++) delete(Edges[i]);
}

Node *Graph::Get_Node(string &s)
{
  map <string, Node *>::iterator nit;
  Node *n;

  nit = N_Map.find(s);
  if (nit != N_Map.end()) return nit->second;

  n = new Node;
  n->name = s;
  Nodes.push_back(n);
  N_Map.insert(make_pair(s, n));
  return n;
}

Edge *Graph::Get_Edge(Node *n1, Node *n2)
{
  map <string, Edge *>::iterator eit;
  Edge *e;
  string name;

  name = n1->name + "->";
  name += n2->name;

  eit = E_Map.find(name);
  if (eit != E_Map.end()) return eit->second;

  e = new Edge;
  e->name = name;
  e->n1 = n1;
  e->n2 = n2;
  e->original = 0;
  e->residual = 0;
  e->flow = 0;
  e->reverse = NULL;
  
  Edges.push_back(e);
  E_Map.insert(make_pair(name, e));
  return e;
}

main()
{
  Graph *g;
  double f;

  g = new Graph();
  f = g->Find_Max_Flow();
  printf("Max flow is %.3lf\n", f);
}