import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;

class Main {
	static PrintWriter out = new PrintWriter(System.out);
	static String str;

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int d = Integer.parseInt(br.readLine());
		String[] num = br.readLine().split(" ");
		br.close();
		int[] result = new int[d + 1];

		PrintWriter out = new PrintWriter(System.out);

		int i;
		if (d < 3) {
			out.println(d);
			for (i = 0; i < d; i++) {
				out.print(num[i] + " ");
			}
			out.println(num[i]);
		} else {
			for (i = 0; i < d + 1; i++) {
				result[i] = Integer.parseInt(num[i]);
			}
			for (i = d; i > 2; i--) {
				result[i - 2] -= -result[i];
			}
			int point = 0;
			for (i = 0; i < 3; i++) {
				if (result[i] != 0) {
					point = i;
				}
			}
			out.println(point);
			for (i = 0; i < point; i++) {
				out.print(result[i] + " ");
			}
			out.print(result[i]);

		}
		out.flush();
	}
}