import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        long N = scanner.nextLong();
        boolean hasEven = false;
 
        for (int i = 1; i <= N; i++) {
            if (i % 2 == 0) {
                System.out.println(i);
                hasEven = true;
            }
        }
 
        if (!hasEven) {
            System.out.println(-1);
        }
 
        scanner.close();
    }
}
 

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