#include <iostream>
#include <vector>
using namespace std;

int main() {
    int N;
    cin >> N;
    vector<int> a(N + 1);
    for (int i = 0; i <= N; ++i) cin >> a[i];

    for (int i = N; i >= 3; --i) {
        a[i - 2] += a[i];
    }

    int D = 0;
    for (int i = 2; i >= 0; --i) {
        if (a[i] != 0) {
            D = i;
            break;
        }
    }

    cout << D << endl;
    for (int i = 0; i <= D; ++i) {
        cout << a[i] << " ";
    }
    cout << endl;
}