#include <bits/stdc++.h>
using namespace std;
// 方針:
// x^3 - x = (x - 1)x(x + 1) を利用して代入法で解決
int main() {
	#ifdef DEBUG
	std::ifstream in("/home/share/inputf.in");
	std::cin.rdbuf(in.rdbuf());
	#endif
	int D;
	cin >> D;
	D++;
	int64_t a, b, c;
	vector<int> A(D);
	// s = A(1), t = A(-1)
	int s = 0, t = 0;
	for(int i = 0; i < D; i++) {
		cin >> A[i];
		s += A[i];
		t += (1 - (i % 2) * 2) * A[i];
	}
	c = A.front();
	a = (s + t - 2 * c) / 2;
	b = (s - t) / 2;
	if(a == 0) {
		if(b == 0) {
			cout << 0 << endl;
			cout << c;
		} else {
			cout << 1 << endl;
			cout << c << " " << b;
		}
	} else {
		cout << 2 << endl;
		cout << c << " " << b << " " << a;
	}
	return 0;
}