// by Alex Prohnitchi
#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;

const ll mod=1e9+7;
const ll INF=2e9;

const int dx[] = {0, 1, 0, -1};
const int dy[] = {1, 0, -1, 0};

#define all(x) x.begin(),x.end()
#define allr(x) x.rbegin(),x.rend()
#define rc(x)  return cout<<x<<"\n",0
#define sz(s)  (int) s.size()
#define pb push_back
#define mp make_pair
#define fr first
#define sc second
#define PI 3.14159265358979

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int rand(int l,int r){return uniform_int_distribution<int>(l,r)(rng);}

ifstream fin("reguli.in");
ofstream fout("reguli.out");

int t,n;

void solve() {
	fin >> n;
	int a[n+2];
	vector<int>dif;
	for (int i=1; i<=n; i++) {
		fin >> a[i];
	}
	for (int i=2; i<=n; i++) {
		dif.pb(a[i]-a[i-1]);
	}
	int m=sz(dif);
	int pref[m+2];
	pref[1]=0;
	int j=0;
	int ans=2e6;
	for (int i=2; i<=m; i++) {
		while (j>0 && a[j]!=dif[i-1]) {
			j=pref[j];
		}
		if (dif[j]==dif[i-1])j++;
		pref[i]=j;
		if (j>0) {
			ans=min(i-pref[i],ans);
		}
	}
	fout << ans << '\n';
	for (int i=0; i<ans; i++) {
		fout << dif[i] << '\n';
	}
}

int main() {
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	t=1;
//	cin >> t;
	while (t--) {
		solve();
	}

}