#define _USE_MATH_DEFINES
#include <algorithm>
#include <cstdio>
#include <functional>
#include <iostream>
#include <cfloat>
#include <climits>
#include <cstring>
#include <cmath>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <vector>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;
typedef pair<ll, int> ll_i;
typedef pair<double, int> d_i;
typedef pair<ll, ll> ll_ll;
typedef pair<double, double> d_d;
struct edge { int u, v, y, m; };

ll MOD = 1000000007;
ll _MOD = 1000000009;
double EPS = 1e-10;

int main() {
	int D; cin >> D;
	vector<int> a(D + 1);
	for (int i = 0; i <= D; i++)
		cin >> a[i];
	int y0 = a[0], y1 = 0, y_1 = 0;
	for (int i = 0; i <= D; i++) {
		y1 += a[i];
		y_1 += (i % 2 == 0 ? a[i] : -a[i]);
	}
	int b0 = y0, b1 = (y1 - y_1) / 2, b2 = y1 - b0 - b1;
	if (b2 == 0 && b1 == 0)
		cout << 0 << endl << b0 << endl;
	else if (b2 == 0 && b1 != 0)
		cout << 1 << endl << b1 << ' ' << b0 << endl;
	else if (b2 != 0 && b1 != 0)
		cout << 2 << endl << b2 << ' ' << b1 << ' ' << b0 << endl;
}