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

int main() {
    int d,e;
    vector<int> m;
    cin >> d;

    for (int i=0; i <= d; i++) {
        cin >> e;
        m.push_back(e);
    }


    while (d>2){

        if(m[d]!=0){
            m[d-2] += m[d];
        }
        d--;
    }



    if (m[2] == 0){
        if (m[1] == 0) {
            cout<<0<<endl;
            cout << m[0] << endl;
        } else {
            cout<<1<<endl;
            cout << m[0]<< " "  << m[1] <<endl;
        }
    } else {
        cout<<2<<endl;
        cout << m[0] << " " << m[1]<< " "  << m[2] << endl;
    }

    return 0;
}