EvenNumbers

import java.util.Scanner;

public class EvenNumbers {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        String input = scanner.nextLine().replaceAll("\\D+", " ");

        String[] numbers = input.split(" ");
        long maxEven = -1;

        for (int i = 0; i < numbers.length; i++) {
            try {
                long currentEven = Long.parseLong(numbers[i]);
                if (currentEven % 2 == 0 && currentEven > maxEven) {
                    maxEven = currentEven;
                }
            } catch (NumberFormatException e) {
                //
            }
        }
        System.out.println(maxEven);

    }
}