#include <iostream>

using namespace std;

int D;
int a[10001];

int main() {
	cin >> D;
	for (int i = 0; i <= D; i++) {
		cin >> a[i];
	}
	for (int i = D; i >= 3; i--) {
		a[i - 2] += a[i];
	}
	int DD = 0;
	for (int i = 2; i > 0; i--) {
		if (a[i] != 0) {
			DD = i;
			break;
		}
	}
	cout << DD << endl;
	for (int i = 0; i < DD; i++) {
		cout << a[i] << " ";
	}
	cout << a[DD] << endl;
	return 0;
}