public class QnA {
  ArrayList<Question> questions;
  ArrayList<Answers> answers;
  ArrayList<Items> items;
  QnA() {
    this.questions = new ArrayList<Question>();
    this.answers = new ArrayList<Answers>();
    this.items = new ArrayList<Answers>();
  }

  boolean PostQuestion(int itemId, String ques) {
    try {
      Item item = items.get(itemId);
      Question q = new Question(itemId, ques);
      this.questions.add(q);
    } catch (IndexOutOfBoundException) {
      return false;
    }
    return true;
  }
  
  boolean PostAnswer(int qid, int itemId, String ques) {
    try {
      Question q = questions.get(qid); 
      Answer a = new Answer(qid, itemId, ques);
      this.questions.add(q);
      q.ans.add(a);
    } catch (IndexOutOfBoundException) {
      return false;
    }
    return true;
  }
  // upvoteQuestion()
  // upvoteAnswer()
}

class Question {
  int itemId;
  string ques;
  static int qctr = 0;
  int id;
  ArrayList<Answers> ans;
  Question(int itemId, String ques) {
    this.id = qctr++;
    this.ques = ques;
    this.itemId = itemId;
    this.ans = new ArrayList<Answers>();
  }
}

class Answer {
  int qid;
  int id;
  String ans;
  static int actr = 0;
  int itemId;
  Answer(int qid, int itemId, String ans) {
    this.id = actr++;
    this.itemId = itemId;
    this.ans = ans;
  }
}

class Item {
  ArrayList<Question> qs;
}

main() {
  QnA qna = new QnA();
  if(!qna.postQuestion(1, "what is the product price")) {
    System.out.println("Invalid Item Id");
  }
  if (!qna.postAnswer(1, 1, "its 19.4")) {
    System.out.println("Invalid Question Id");
  }
}