#include<bits/stdc++.h>

#define all(s) s.begin(),s.end()
#define rc(x) return cout<<x<<endl,0
#define forn(i,n) for(int i=0;i<int(n);i++)

#define pb push_back
#define mp make_pair
#define fr first
#define sc second

typedef long long ll;
typedef long double ld;

const int nmax=1e6+3;
const int mod=998244353;
const ll inf=0x3f3f3f3f3f3f3f3f;

using namespace std;

int main()
{
  freopen("reguli.in","r",stdin);
  freopen("reguli.out","w",stdout);
  ios_base::sync_with_stdio(0); cin.tie(0);
  int n;
  cin>>n;
  vector<int> v;
  for(int i=1;i<=n;i++)
  {
    int x;
    cin>>x;
    v.pb(x);
  }
  vector<int>a;
  for(int i=1;i<n;i++)
  {
    a.pb(v[i]-v[i-1]);
  }
  vector<int> p(n,0);
  int c=0;
  for(int i=1;i<n-1;i++)
  {
    while(c>0 && a[i]!=a[c]) c=p[c-1];
    if(a[i]==a[c]) c++;
    p[i]=c;
  }
  int k=n-1;
  int sol=0;
    for(int i=k-1;i>=0;i--)
    {
      if(p[i]!=0 && (i+1)%(i-p[i]+1)==0)
      {
        sol=(i+1)/2;
        cout<<sol<<"\n";
        for(int j=i-sol+1;j<i+1;j++) cout<<a[j]<<"\n";
        return 0;
      }
    }
}