#include <iostream>
using namespace std;

int main(){
	int d;
	cin >> d;
	int a[d + 1];
	for(int i = 0; i <= d; i++) cin >> a[i];
	for(int i = d; i >= 3; i--){
		a[i - 2] += a[i];
		a[i] = 0;
	}
	int ans = a[2] ? 2 : a[1] ? 1 : 0;
	cout << ans << endl;
	for(int i = 0; i <= ans; i++) cout << a[i] << ' ';
	cout << endl;
}