#include <bits/stdc++.h>

#define show(x) cout << #x << " = " << x << endl

using namespace std;
using ll = long long;
using pii = pair<int, int>;
using vi = vector<int>;

template <typename T>
ostream& operator<<(ostream& os, const vector<T>& v)
{
    os << "sz=" << v.size() << "\n[";
    for (const auto& p : v) {
        os << p << ",";
    }
    os << "]\n";
    return os;
}

template <typename S, typename T>
ostream& operator<<(ostream& os, const pair<S, T>& p)
{
    os << "(" << p.first << "," << p.second
       << ")";
    return os;
}


constexpr ll MOD = 1e9 + 7;

template <typename T>
constexpr T INF = numeric_limits<T>::max() / 100;

int main()
{
    int D;
    cin >> D;
    int alpha = 0;
    int beta = 0;
    int gamma = 0;
    for (ll i = 0; i <= D; i++) {
        int a;
        cin >> a;
        alpha += a;
        if (i == 0) {
            beta = a;
        }
        gamma += ((i % 2 == 0) ? a : -a);
    }
    const int a0 = beta;
    const int a1 = (alpha - gamma) / 2;
    const int a2 = (alpha + gamma) / 2 - beta;
    if (a2 != 0) {
        cout << 2 << endl;
        cout << a0 << " " << a1 << " " << a2 << endl;
    } else if (a1 != 0) {
        cout << 1 << endl;
        cout << a0 << " " << a1 << endl;
    } else {
        cout << 0 << endl;
        cout << a0 << endl;
    }
    return 0;
}