#include <iostream>
#include <vector>
#include <string>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <algorithm>	// require sort next_permutation count __gcd reverse etc.
#include <cstdlib>	// require abs exit atof atoi 
#include <cstdio>		// require scanf printf
#include <functional>
#include <numeric>	// require accumulate
#include <cmath>		// require fabs
#include <climits>
#include <limits>
#include <cfloat>
#include <iomanip>	// require setw
#include <sstream>	// require stringstream 
#include <cstring>	// require memset
#include <cctype>		// require tolower, toupper
#include <fstream>	// require freopen
#include <ctime>		// require srand
#define rep(i,n) for(int i=0;i<(n);i++)
#define ALL(A) A.begin(), A.end()

using namespace std;

typedef long long ll;
typedef pair<int, int> P;

int main()
{
	ios_base::sync_with_stdio(0);
	int D; cin >> D;
	vector<int> a(D+1, 0 );
	rep (i, D+1 ) cin >> a[i];

	int b, c, d;
	int sum1 = accumulate (ALL (a ), 0 );
	int sum2 = 0;
	for (int i = D; i >= 0; i-- ){
		if (i % 2 == 0 )
			sum2 += a[i];
		else
			sum2 -= a[i];
	} // end for

	d = a[0];
	b = (sum1 + sum2 )/2 - d;
	c = (sum1 - sum2 )/2;

	int cnt = 0;
	if (c != 0 ) cnt = 1;
	if (b != 0 ) cnt = 2;

	cout << cnt << endl;
	if (cnt == 0 ){
		cout << d << endl;
	}else
	if (cnt == 1 ){
		cout << d << ' ' << c << endl;
	}else{ // if (cnt == 2 )
		cout << d << ' ' << c << ' ' << b << endl;
	} // end if
			
	return 0;
}