#include <iostream>
#include <algorithm>
#include <vector>

int main() {

  long i, j, k;
  long ans[3];
  long count = 0;
  std::string str;
  std::vector<long> v;
  long temp;
  
  long D;

  std::cin >> D;

  for(i = 0; i < D+1; i++) {
    std::cin >> temp;
    v.push_back(temp);
  }

  ans[0] = v[0];
  ans[1] = 0;
  for(i = 1; i < D+1; i+=2) {
    ans[1] += v[i];
  }
  ans[2] = 0;
  for(i = 2; i < D+1; i+=2) {
    ans[2] += v[i];
  }

  if(ans[2] != 0) {
    std::cout << 2 << std::endl;
    std::cout << ans[0] << " " << ans[1] << " " << ans[2] << std::endl;
    return 0;
  }

  if(ans[1] != 0) {
    std::cout << 1 << std::endl;
    std::cout << ans[0] << " " << ans[1] << std::endl;
    return 0;
  }

  if(ans[0] != 0) {
    std::cout << 0 << std::endl;
    std::cout << ans[0] << std::endl;
    return 0;
  }

  std::cout << 0 << std::endl;
  std::cout << 0 << std::endl;
  return 0;
  
}