#include <fstream>

using namespace std;
ifstream f("reguli.in");
ofstream g("reguli.out");
int n,v[500005];
int dif[500005];
int lps[500005];
int main()
{
    int i,k=1,nr;
    f>>n;
    for (i=1;i<=n;i++)
        f>>v[i];
        for (i=2;i<=n;i++)
        dif[i-1]=v[i]-v[i-1];
    for (i=2;i<=n-1;i++)
    {
        while (k>1 && dif[i]!=dif[k]) k=lps[k];
        if (dif[i]==dif[k]) k++;
        lps[i]=k-1;
    }
    nr=n-lps[n-1]-1;
    g<<nr<<'\n';
    for (i=1;i<=nr;i++)
        g<<dif[i]<<'\n';
    return 0;
}