#include <iostream>
#include <algorithm>
using namespace std;
int main()  
{
    int n;
    while (cin>>n) {
        vector<int> a(n+1);
        for(int& v: a) cin>>v;
        reverse(begin(a), end(a));

        for(int i=0;i+2<n;++i) {
            a[i+2]+=a[i];
            a[i]=0;
        }

        int k=0;
        for(int i=0;i<4;++i) if (!a[n-i]) { k=i; break; }
        cout<<max(0,k-1)<<endl;
        for(int i=0;i<max(1,k);++i) cout<<a[n-i]<<' ';
        cout<<endl;
    }
}