#include <fstream>
#define MAX 500000
using namespace std;
ifstream cin ("reguli.in");
ofstream cout ("reguli.out");
int pi[MAX + 10], n;
long long v[MAX + 10];
void kmp()
{
    int k = 0;
    pi[0] = 0;
    for (int i = 1; i < n - 3; i++)
    {
        while (k != 0 && v[k] != v[i])
            k = pi[k - 1];
        if (v[k] == v[i])
            k++;
        pi[i] = k;
    }
}
int main()
{
    long long val1, val2;
    cin >> n >> val1;
    for (int i = 1; i < n; i++)
    {
        cin >> val2;
        v[i - 1] = val2 - val1;
        val1 = val2;
    }
    kmp();
    int l = n - 3 - pi[n - 4];
    cout << l << '\n';
    for (int i = 0; i < l; i++)
        cout << v[i] << '\n';
    return 0;
}