class Node:
    def __init__(self, text, is_answer=False):
        self.text = text
        self.is_answer = is_answer
        self.yes_branch = None
        self.no_branch = None

class KnowledgeSystem:
    def __init__(self):
        self.root = None
        self.num_answers = 0

    def load_rules(self, lines):
        # Initialize index for lines
        index = 0

        # Recursive function to parse lines into a binary tree
        def parse_node():
            nonlocal index
            if index >= len(lines):
                raise ValueError("Chyba: Neočakávaný koniec pravidiel.")
            line = lines[index].strip()
            index += 1

            if not line:
                return None

            is_answer = line.startswith("*")
            text = line[1:].strip() if is_answer else line

            node = Node(text, is_answer)
            if is_answer:
                self.num_answers += 1
                return node
            node.yes_branch = parse_node()  # Process yes branch
            node.no_branch = parse_node()   # Process no branch
            return node

        # Parse the tree from the first line
        self.root = parse_node()

    def ask_questions(self):
        current = self.root
        while current:
            print(current.text)
            if current.is_answer:
                print("Koniec.")
                break
            answer = input("Odpovedajte 'a' pre prvú možnosť alebo 'n' pre druhú možnosť: ").strip().lower()
            if answer == 'a':
                current = current.yes_branch
            elif answer == 'n':
                current = current.no_branch
            else:
                print("Neplatná odpoveď, koniec.")
                break

def main():
    lines = []
    print("Zadajte bázu pravidiel (prázdny riadok pre koniec):")
    while True:
        line = input()
        if not line.strip():
            break
        lines.append(line)

    # Initialize knowledge system and load rules
    ks = KnowledgeSystem()
    try:
        ks.load_rules(lines)
        print(f"Pozná {ks.num_answers} druhov ovocia a zeleniny.")
        ks.ask_questions()
    except ValueError as e:
        print(e)

if __name__ == "__main__":
    main()