#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
//#include<cctype>
#include<climits>
#include<iostream>
#include<string>
#include<vector>
#include<map>
//#include<list>
#include<queue>
#include<deque>
#include<algorithm>
//#include<numeric>
#include<utility>
#include<complex>
//#include<memory>
#include<functional>
#include<cassert>
#include<set>
#include<stack>

const int dx[] = {1, 0, -1, 0};
const int dy[] = {0, 1, 0, -1};
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef pair<int, int> pii;

int a[10010];

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int D;
    cin >> D;
    for (int i = 0; i <= D; i++) cin >> a[i];
    reverse(a, a+D+1);
    for (int i = 0; i <= D-3; i++) {
        a[i+2] += a[i];
        a[i] = 0;
    }
    if (a[D-2]) {
        cout << 2 << endl;
        cout << a[D] << " " << a[D-1] << " " << a[D-2] << endl;
    } else if (a[D-1]) {
        cout << 1 << endl;
        cout << a[D] << " " << a[D-1] << endl;
    } else {
        cout << 0 << endl;
        cout << a[D] << endl;
    }
    return 0;
}