#include <bits/stdc++.h>

using namespace std;

typedef unsigned long long ull;
typedef long long ll;

int main(){
	int d;
	cin >> d;
	int a[d+1];
	for(int i=0; i<d+1; i++) cin >> a[i];
	int x=0, y=0;
	for(int i=0; i<d+1; i++) x+=a[i];
	for(int i=0; i<d+1; i++){
		if(i%2==0) y+=a[i];
		else y-=a[i];
	}
	int r[3];
	r[0]=a[0];
	r[1]=(x-y)/2;
	r[2]=(x+y)/2-r[0];
	if(r[2]!=0){
		cout << 2 << endl;
		cout << r[0] << " " << r[1] << " " << r[2] << endl;
	}else if(r[1]!=0){
		cout << 1 << endl;
		cout << r[0] << " " << r[1] << endl;
	}else{
		cout << 0 << endl;
		cout << r[0] << endl;
	}
	return 0;
}