#include <bits/stdc++.h>
using namespace std;
int a[11000];
int main(){
int d;
cin >> d;
for(int i = 0; i <= d; ++i) {
cin >> a[i];
}
for (int i = d; i >= 3; --i) {
 a[i - 2] += a[i];
}
int q = 2;
while (q >= 1 && a[q] == 0) q--;
cout << q << endl;
for(int i=0;i<=q;i++) {
cout << a[i] << (i == q ? "\n" : " ");
}
}