#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  // P(x) = (x - 1) Q1(x) + R1(x) => P( 1) = R1( 1)
  // P(x) = (x + 1) Q2(x) + R2(x) => P(-1) = R2(-1)
  // P(x) =  x      Q3(x) + R3(x) => P( 0) = R3( 0)
  // P(x) = (x^3 - x) Q(x) + ax^2 + bx + c
  // P(1) = a + b + c = R1(1)
  // P(-1) = a - b + c = R2(-1)
  // P(0) = c = R3(0)
  // a = (R1(1) + R2(-1)) / 2 - c
  // b = R1(1) - a - c
  // c = R3(0)
  int n;
  cin >> n;
  vector<int> d(n + 1);
  rep(i, n + 1) cin >> d[i];
  int p1 = 0, p2 = 0;
  rep(i, n + 1) {
    p1 += d[i];
    p2 += d[i] * (i % 2 == 1 ? -1 : 1);
  }
  int c = d[0];
  // p1 - p2 は a[i] * 0 or a[i] * 2 の差なので偶数になるはず
  assert((p1 + p2) % 2 == 0);
  int a = (p1 + p2) / 2 - c;
  int b = p1 - a - c;
  if (a == 0 && b == 0) {
    cout << 0 << endl;
    cout << c << endl;
  }
  else if (a == 0) {
    cout << 1 << endl;
    cout << c << ' ' << b << endl;
  }
  else {
    cout << 2 << endl;
    cout << c << ' ' << b << ' ' << a << endl;
  }
  return 0;
}