#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
#include <list>
#include <set>
#include <map>
#include <numeric>
#include <regex>
#include <tuple>
#include<iomanip>
using namespace std;

typedef long long ll;
typedef pair<int, int> P;
#define MOD 1000000007 // 10^9 + 7
#define INF 1000000000 // 10^9
#define LLINF 1LL<<60

int a[10009];

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	int D; cin >> D;
	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;
	}

	if (D >= 3) {
		int ans = 2;
		for (int i = 2; i >= 0; i--) {
			if (a[i] == 0) ans--;
			else break;
		}

		ans = max(ans, 0);

		cout << ans << endl;
		for (int i = 0; i <= ans; i++) {
			cout << a[i] << " ";
		}
	}
	else {
		cout << 2 << endl;
		for (int i = 0; i < 3; i++) cout << a[i] << " ";
	}

	cout << endl;

	return 0;
}