#include "bits/stdc++.h"
using namespace std;

int main() {
	int D;
	cin >> D;
	vector<int> b(D + 1);
	for (int i = 0; i < D + 1; i++)
	{
		cin >> b[i];
	}
	for (int i = D; i >= 3; i--)
	{
		b[i - 2] += b[i];
		b[i] = 0;
	}
	int ans = 0;
	if (b[2]){
		ans = 2;
	}
	else if (b[1]){
		ans = 1;
	}
	cout << ans << endl;
	for (int i = 0; i <= ans; i++)
	{
		if (i == ans) cout << b[i] << endl;
		else cout << b[i] << " ";
	}
}