#include <bits/stdc++.h>
using namespace std;

signed main(){
  int D; cin >> D;
  vector< int > B( D + 1 );
  for( int i = 0; i <= D; ++i )
    cin >> B[ i ];
  for( int i = D; i >= 3; --i )
    B[ i - 2 ] += B[ i ],
    B[ i ] = 0;
  int lst;
  for( lst = D; lst >= 1; --lst )
    if( B[ lst ] != 0 )
      break;
  cout << lst << endl;
  for( int i = 0; i <= lst; ++i )
    cout << B[ i ] << " \n"[ i == lst ];
  return 0;
}