#include <iostream>
#include <vector>

void solve() {
    int n;
    std::cin >> n;

    std::vector<int> xs(n + 1);
    for (auto& x : xs) std::cin >> x;

    while (n - 3 >= 0) {
        xs[n - 2] += xs[n];
        xs.pop_back();
        --n;
    }

    while (xs.size() > 1 && xs.back() == 0) xs.pop_back();

    std::cout << xs.size() - 1 << std::endl;
    for (auto x : xs) std::cout << x << " ";
    std::cout << std::endl;
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}