// #include <iostream>

#include <fstream>
#include <climits>

using namespace std;

ifstream cin("reguli.in");
ofstream cout("reguli.out");

int a[500001],n,m;
int lps[500001];

int main()
{
	cin >> n;
	int x, y;
	cin >> x;
	for (int i = 1; i < n; i++)
	{
		cin >> y;
		a[m++] = y - x;
		x = y;
	}
	int q = 0;
	int l = 0;
	for (int i = 2; i <= m; i++)
	{
		while (q && a[q] != a[i - 1])
			q=lps[q];
		if (a[q] == a[i - 1])
			q++;
		lps[i] = q;
	}
	for (int i = 1; i <= m; i++)
		if (i % (i - lps[i]) == 0 && i / (i - lps[i]) > 1)
			l = max(l,i - lps[i]);
	cout << l << '\n';
	for (int i = 0; i < l; i++)
		cout << a[i] << '\n';
	return 0;
}