public static String solve2(InputStream in){

    // Read first line of input
    int nV = 0;
    int mE = 0;
    int startV = 0;
    int endV = 0;
    Scanner sc =  new Scanner(in);

    if(sc.hasNextLine()){
      nV = sc.nextInt();
      mE = sc.nextInt();
      startV = sc.nextInt();
      endV =  sc.nextInt();
    }

    // Create the Node List
    Node[] list = readData2(sc, nV);
    sc.close();
    if (mE == 0) return "no";
    if (nV == 0) return "no";
    if (startV==endV) return "yes";
    Node startNode = list[startV-1];
    Node endNode = list[endV-1];

    Queue<Node> queue  = new LinkedList<>();

    queue.offer(startNode);

    while(queue.size()!=0){
      Node current = queue.poll();
      if(endNode == current) return "yes";
      current.marked = true;

      for(int i=0; i < current.outEdges.size();i++)
        if(current.outEdges.get(i).marked==false) queue.offer(current.outEdges.get(i));
    }

    return "no";
  }

  public static Node[] readData2(Scanner sc, int size){
    Node[] list = new Node[size];
    while(sc.hasNextLine()){
      //get the node
      int nodeAt = sc.nextInt() - 1;
      int edgeTo = sc.nextInt() - 1;

      if(list[edgeTo]==null) {
        list[edgeTo] = new Node();
      }

      if(list[nodeAt]==null) {
        list[nodeAt] = new Node();
      }
      list[nodeAt].outEdges.add(list[edgeTo]);
      // Ignore the rest
      sc.nextLine();
    }
    sc.close();
    return list;
  }

}