#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <climits>
#include <cfloat>
#include <map>
#include <utility>
#include <set>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
#include <iomanip>
using namespace std;
#define INF 1e9
#define PI acos(-1)
typedef long long ll;


int main() {
	
	int d; cin >> d;
	vector<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];
	}

	int num = 2;
	if (a[2] == 0)num--;
	if (a[1] == 0 && num == 1)num--;
	
	cout << num << endl;
	for (int i = 0; i <= num; i++) {
		if (i == num)cout << a[num] << endl;
		else cout << a[i] << " ";
	}

	return 0;
}