#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <map>
#include <sstream>
#include <fstream>
#include <queue>
#include <math.h>
#include <set>

#define For(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n)  For(i,0,n)

//clear memory
#define CLR(a) memset((a), 0 ,sizeof(a))
#define check(a) rep(i, a.size()) cout << a[i] << endl
#define SORT(c) sort((c).begin(),(c).end())
using namespace std;

int main(int argc, char* argv[]){
	int n;
	cin >> n;
	vector<int> v(n + 1);
	rep(i, n + 1){
		cin >> v[i];
	}
	for (int i = n; i > 2; i--){
		if (v[i] == 0) continue;
		v[i - 2] += v[i];
		v[i] = 0;
	}
	int count = 0;
	for (int i = min(3, n); i > 0; i--){
		if (v[i] != 0){
			count = i;
			break;
		}
	}

	if (count == 0)cout << 0 << endl ;
	else cout << count << endl;
	for (int i = 0; i < count + 1; i++){
		cout << v[i];
		if (i == count){
			cout << endl;
			break;
		}cout << " ";
	}


	return 0;
}