#include <iostream>
#include <vector>

using namespace std;

#define REP(i,first,last) for (int i=first;i<last;i++)

int D;
vector<int> multi;

int main(){
  cin >> D;

  int val;
  REP(i,0,D + 1) {
    cin >> val;
    multi.push_back(val);
  }

  for (int i=multi.size() - 1;i>=3;i--) {
    if (multi[i] != 0) {
      multi[i-2] += multi[i];
      multi[i] = 0;
    }
  }

  int top_idx = 0;
  for (int i=multi.size() - 1;i>=0;i--) {
    if (multi[i] != 0) {
      top_idx = i;
      break;
    }
  }

  cout << top_idx << endl;

  for (int i=0;i<=top_idx;i++) {
    if (i == 0) {
      cout << multi[i];
    } else {
      cout << " " << multi[i];
    }
  }
  cout << endl;
}