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

int main(void) {
	int D;
	cin >> D;
	vector<int> a(D + 1);
	for(int i = 0; i <= D; ++i) cin >> a[i];
	
	for(int i = D; i >= 3; --i) a[i - 2] += a[i], a[i] = 0;
	
	int ans = 0;
	for(int i = 0; i <= D; ++i) if(a[i] != 0) ans = max(ans, i);
	
	cout << ans << "\n";
	for(int i = 0; i <= ans; ++i) cout << a[i] << " ";
	cout << "\n";
	return 0;
}