private static Node readTrie() {
		// leaf
		if (BinaryStdIn.readBoolean()) {
		  char c = BinaryStdIn.readChar(8);
		  return new Node(c, 0, null, null);
		}
		  
		Node l = readTrie(); 
		Node r = readTrie();
		return new Node('\0', 0, l, r);
	}