#include <bits/stdc++.h>
#define all(cont) cont.begin(), cont.end()
#define pb push_back
#define fi first
#define se second
#define DEBUG(x) cerr << (#x) << ": " << (x) << '\n'
 
using namespace std;
 
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef long long ll;
typedef unsigned long long ull;
 
template<class T> bool uin(T &a, T b) {return (a < b ? false : (a = b, true));}
template<class T> bool uax(T &a, T b) {return (a > b ? false : (a = b, true));}
 
ifstream f("reguli.in");
ofstream g("reguli.out");
 
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
#ifdef LOCAL_DEFINE
  freopen(".in", "r", stdin);
#endif
 
  int n;
  f >> n;
  vector<long long> x(n);
  for (auto &val : x) {
    f >> val;
  }
  
  vector<long long> a(n);
  for (int i = 1; i < n; ++i) {
    a[i] = x[i] - x[i - 1];
  }
  
  vector<int> pi(n);
  pi[1] = 0;
  int k = 0;
  for (int i = 2; i < n; ++i) {
    while (k && a[k + 1] != a[i]) {
      k = pi[k];
    }
    if (a[k + 1] == a[i]) {
      ++k;
    }
    pi[i] = k;
  }
  
  k = n - k - 1;
  
  g << k;
  for (int i = 1; i <= k; ++i) {
    g << '\n' << a[i]; 
  }
  g << endl;
  
  f.close();
  g.close();
 
#ifdef LOCAL_DEFINE
  cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
#endif
  return 0;
}