#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vi  = vector<int>; using vb  = vector<bool>; using vd  = vector<double>; using vl  = vector<ll>;
using vvi = vector<vi>;  using vvb = vector<vb>;   using vvd = vector<vd>;     using vvl = vector<vl>;

#define REP(i,n) for(ll i=0; i<(n); ++i)

int main() {
	ll d; cin >> d;
	vl a(d + 1); REP(i, d + 1) cin >> a[i];
	for (ll i = d; i >= 3; --i) a[i - 2] += a[i];

	ll nd = a[2] != 0 ? 2 :
	          a[1] != 0 ? 1 : 0;
	cout << nd << endl;
	REP(i, nd) cout << a[i] << " ";
	cout << a[nd] << endl;

	return 0;
}