public class Alphabets {

  public static void main(String[] args) throws Throwable {
    final AN an = new AN(false);
    new Thread(an::Alpha).start();
    new Thread(an::numbers).start();
  }
}

class AN {

  boolean flag;

  AN(boolean flag) {
    this.flag = flag;
  }

  synchronized void Alpha() {
    for (char i = 'A'; i <= 'Z'; i++) {
      if (flag == false) {
        System.out.print(+i + " ");
        notifyAll();
        flag = true;
      }
      if (i != 'Z') {
        try {
          wait();
        } catch (InterruptedException ex) {
        }
      }
    }
  }

  synchronized void numbers() {
    for (int i = 1; i <= 26; i++) {
      if (flag == true) {
        System.out.print(+i + " ");
        notifyAll();
        flag = false;
      }
      if (i != 26) {
        try {
          wait();
        } catch (InterruptedException ex) {
        }
      }
    }
  }
}