#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000

int main(){
	
	int D;
	cin>>D;
	
	vector<long long> a(D+1);
	rep(i,D+1)cin>>a[i];
	
	while(a.size() >= 4){
		long long t = a.back();
		a.pop_back();
		a[a.size()-2] += t;
	}
	
	while(a.size()>0&&a.back()==0)a.pop_back();
	if(a.size()==0)a.push_back(0);
	cout<<a.size()-1<<endl;
	
	rep(i,a.size()){
		if(i!=0)cout<<' ';
			cout<<a[i];
	}
	cout<<endl;
	
	return 0;
}