#include <bits/stdc++.h>
#define NMAX 500005
#define ll long long

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

int n;
int S[NMAX];
ll key[NMAX];

void kmp()
{
    S[0] = -1, S[1] = 0;
    for (int i = 2; i <= n; i++)
    {
        int prv = i - 1;
        ll ch = key[i];

        while (S[prv] != -1 && key[S[prv] + 1] != ch)
            prv = S[prv];
        S[i] = S[prv] + 1;
    }
}

int main()
{
    ll p, a;

    fin >> n >> p;
    n--;
    for (int i = 1; i <= n; i++)
    {
        fin >> a;
        key[i] = a - p;
        p = a;
    }
    kmp();

    int fn = n - S[n];

    fout << fn << "\n";
    for (int i = 1; i <= fn; i++)
        fout << key[i] << "\n";

    return 0;
}