#include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<strings.h>
using namespace std;
#define LL long long
int b[10010];
int main(){
	int d;
	cin>>d;
	for(int i=0;i<=d;i++)cin>>b[i];
	for(int i=d;i>=3;i--){
		b[i-2]+=b[i];
		b[i]=0;
	}
	while(d>0&&b[d]==0)d--;
	cout<<d<<endl;
	cout<<b[0];
	for(int i=1;i<=d;i++)
		cout<<" "<<b[i];
	cout<<endl;
}