#include<iostream>
#include<vector>
#include<string>
#include<algorithm>	
#include<map>
#include<set>
#include<utility>
#include<cmath>
#include<cstring>
#include<queue>
#include<stack>
#include<cstdio>
#include<sstream>
#include<iomanip>
#include<assert.h>
#include<ctime>
#include<cstdlib>
#include<numeric>
using namespace std;
typedef long long ll;
#define loop(i,a,b) for(ll i=a;i<b;i++)
#define rloop(i,a,b) for(int i=a;i>=b;i--)
const int inf=1e8;
const ll INF=1e16;
#define MOD 1000000007
#define mod 1000000009
#define m 1000003

int main(){
	int d;
	cin>>d;
	vector<int> a;
	int temp;
	loop(i,0,d+1){
		cin>>temp;
		a.push_back(temp);
	}
	rloop(i,a.size()-1,3){
		a[i-2]+=a[i];
		a[i]=0;
	}
	vector<int> b;
	b.assign(&a[0],&a[3]);
	int d2;
	if(b[2]!=0){
		cout<<2<<"\n";
		cout<<b[0]<<" "<<b[1]<<" "<<b[2]<<"\n";
	}else if(b[1]!=0){
		cout<<1<<"\n";
		cout<<b[0]<<" "<<b[1]<<"\n";
	}else{
		cout<<0<<"\n";
		cout<<b[0]<<"\n";
	}
}