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 {
			int[] tmp = new int[d + 1];
			for (i = 0; i < d + 1; i++) {
				tmp[i] = Integer.parseInt(num[i]);
				if (i < d - 1) {
					result[i] = tmp[i];
				}
			}
			result[d - 2] -= -tmp[d];
			result[d - 3] -= -tmp[d - 1];

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