#include<iostream>
#include<cassert>
using namespace std;
int D,A[10101];
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cin>>D;
	for(int i=0;i<=D;i++)cin>>A[i];
	for(int i=D;i>=3;i--)A[i-2]+=A[i];
	D=2;
	while(D>=1&&A[D]==0)D--;
	cout<<D<<"\n";
	for(int i=0;i<=D;i++)cout<<A[i]<<(i==D?"\n":" ");
}