#include <fstream>
using namespace std;
ifstream f("reguli.in");
ofstream g("reguli.out");

int x,y;
int v[500000];
int p[500000],n,i,poz;

void prefix()
{
    int k,i;
    p[1]=0;
    for (i=2; i<=poz; i++)
    {
        while (k>0 && v[k+1]!=v[i]) k=p[k];
        if (v[k+1]==v[i]) k++;
        p[i]=k;
    }
    g << poz-p[poz] << endl;
    for (i=1; i<=poz-p[poz]; i++)
        g << v[i] << '\n';
}

int main()
{
    f >> n >> x;
    for (i=1; i<n; i++)
    {
        f >> y;
        v[++poz]=y-x;
        x=y;
    }
    prefix();
}