import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int D = scanner.nextInt();
		int[] a = new int[D + 1];
		for (int i = 0; i < D + 1; i++) {
			a[i] = scanner.nextInt();
		}

		for (int i = D; i >= 3; i--) {
			a[i - 2] += a[i];
			a[i] = 0;
		}

		int ans = 0;
		if (D >= 2 && a[2] != 0) {
			ans = 2;
		} else if (D >= 1 && a[1] != 0) {
			ans = 1;
		}
		System.out.println(ans);
		for (int i = 0; i <= ans; i++) {
			System.out.print(a[i] + " ");
		}
		System.out.println();
	}

}