class Tree
  {
  String tag;         // What kind of node we are.
  String spelling;    // If we're an Id, our spelling.
  int    value;       // If we're a number, our value.
  
  Tree first;         // First child. Other children linked as siblings to this.
  Tree next;          // Our sibling. Forms linked list.
  
/* ------------------------------------------------------------------------- */
  
  // Create a leaf node with a spelling.
  Tree(String s) { tag = "Id"; spelling = s; }

  // Create a leaf node with a value.
  Tree(int v) { tag = "Num"; value = v; }

  // Create a node with one child.
  Tree(String t, Tree c1) { tag = t; first = c1; }

  // Create a node with two children.
  Tree(String t, Tree c1, Tree c2) { tag = t; first = c1; c1.next = c2; }

/* ------------------------------------------------------------------------- */

  // Add more children to a node.
  
  void appendChild(Tree newChild)
    {
    if (first == null)
      first = newChild;       // It's our first child.
    else
      {
      Tree last = first;      // Not really the last child, but will be.
      while (last.next != null) last = last.next;   // Find last child.
      last.next = newChild;   // Now it's the last, so we append to it.
      }
    }

/* ------------------------------------------------------------------------- */

  // Preorder traversal of syntax tree, returning string with indent formatting.
  
  String toStringAll(int depth, String result)
    {
    for (int i = 0; i < depth; i++) result += "| ";  // Indenting.
    
    result += tag + " ";
    if (tag == "Id")
      result += spelling;
    else if (tag == "Num")
      result += new Integer(value).toString();
    result += "\n";
    
    if (first != null) result = first.toStringAll(depth+1, result); // One level deeper.
    if (next  != null) result = next .toStringAll(depth  , result); // Same level.
    
    return result;
    }
 
/* ------------------------------------------------------------------------- */

  // The wrapper the outside world sees. Sets initial indent level to 0.
  
  public String toString() { return toStringAll(0, ""); }
  }

/* ========================================================================= */

class P3
  {
  static Tree prog1()
    {
    Tree sum  = new Tree("Sum", new Tree(5), new Tree(3));      // 5 + 3
    Tree s1   = new Tree("AssignStmt", new Tree("a"), sum);     // a = 5 + 3
    
    Tree prod = new Tree("Product", new Tree(7), new Tree(1));  // 7 * 1
    Tree s2   = new Tree("AssignStmt", new Tree("b"), prod);    // b = 7 * 1
    
    Tree sum2 = new Tree("Sum", new Tree("a"), new Tree("b"));  // a + b
    Tree s3   = new Tree("AssignStmt", new Tree("c"), sum2);    // c = a + b
    
    Tree cmds = new Tree("StatementList", s1);
    cmds.appendChild(s2);
    cmds.appendChild(s3);
    
    return cmds;
    }
    
  public static void main(String[] args)
    {
    System.out.println(prog1());
    }
  }