#include <fstream>

using namespace std;
ifstream f("reguli.in");
ofstream g("reguli.out");

long long x[50001],n,xd[50001],urm[50001];

int main()
{
    int i;
    f>>n;
    for (i=1;i<=n;i++)
        f>>x[i];
    for (i=1;i<n;i++)
        xd[i]=x[i+1]-x[i];
    n--;
    int k=0,nr;
    urm[1]=0;
    for (i=2;i<=n;i++)
    {
        while (k>0 && xd[k+1]!=xd[i]) k=urm[k];
        if (xd[k+1]==xd[i]) k++;
        urm[i]=k;
    }
    nr=n-urm[n];
    g<<nr<<'\n';
    for (i=1;i<=nr;i++) g<<xd[i]<<" ";
    return 0;
}