#include <iostream>

using namespace std;

int D;

int main(){
  cin >> D;
  int a_list[D+1];

  for (int i=0;i<=D;i++) {
    int val;
    cin >> val;
    a_list[i] = val; 
  }

  // Dが3以上なら以下を実行する
  for (int i=D;i>=3;i--) {
    a_list[i-2] += a_list[i];
    a_list[i] = 0;
  }

  if (D == 0 || (a_list[2] == 0 && a_list[1] == 0)) {
    cout<<0<<endl;
    cout<<a_list[0]<<endl;
  } else if (D == 1 || (a_list[2] == 0 && a_list[1] != 0)) {
    cout<<1<<endl;
    cout<<a_list[0]<<" "<<a_list[1]<<endl;
  } else {
    cout<<2<<endl;
    cout<<a_list[0]<<" "<<a_list[1]<<" "<<a_list[2]<<endl;
  }
}