import java.util.*;
public class MyException {

  public static int average(String[] seq) throws BadElementException {
    int sum = 0;

    for (int i = 0; i < seq.length; i++){
      try {
	sum += Integer.parseInt(seq[i]);
      } catch (Exception e) {
	throw new BadElementException("Element is not a number", i);
      }
    }

    return sum / seq.length;
  }

  public static void main(String[] args) {
    try {
      System.out.println(average(args));
    } catch (BadElementException e) {
      System.out.println("Oops, " + args[e.getIndex()] + " isn't a number");
    }
  }
}

class BadElementException extends Exception {
  private int index;

  public BadElementException(String message, int index) {
    super(message);
    this.index = index;
  }

  public int getIndex() {
    return index;
  }
}