#include <bits/stdc++.h>
using namespace std;

int a[ 10010 ];

int main()
{
int i;
int D;
int P;

	cin >> D;
	for( i = 0; i <= D; i++ ) cin >> a[ i ];

	for( i = D; i >= 3; i-- )
	{
		a[ i - 2 ] += a[ i ];
		a[ i ] = 0;
	}

	
	if( a[ 2 ] != 0 )
	{
		cout << 2 << endl;
		cout << a[ 0 ] << " " << a[ 1 ] << " " << a[ 2 ] << endl;
	}
	else if( a[ 1 ] != 0 )
	{
		cout << 1 << endl;
		cout << a[ 0 ] << " " << a[ 1 ] << endl;
	}
	else
	{
		cout << 0 << endl;
		cout << a[ 0 ] << endl;
	}

	return 0;
}