#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    int D; cin >> D;
    vector<ll> a(D + 1);
    rep(i,D+1) cin >> a[i];

    while(a.size() >= 4u) {
        ll x = a.back(); a.pop_back();
        a[a.size() - 2u] += x;
    }

    while(!a.empty() && a.back() == 0) a.pop_back();
    if(a.size() == 0) a.push_back(0);
    cout << a.size() - 1u << endl;
    rep(i,int(a.size())) cout << a[i] << " "; cout << endl;
}