#include <iostream>
using namespace std;
int main(){
	int d; cin >> d;
	int a[11000];

	for (int i = 0; i <= d; ++i) {
		cin >> a[i];
	}
	for (int i = d; i >= 3; --i) {
		a[i - 2] += a[i];
	}
	int q = 2;
	while (q >= 1 && a[q] == 0) q--;
	cout << q << endl;
	for (int i = 0; i <= q; i++) {
		cout << a[i] << (i == q ? "\n" : " ");
	}
}