#include<algorithm>
using namespace std;

#define DIM 1001

int n,pi[DIM],a[DIM];

void kmp ()
{
    int i,q=0;

    for(i=2;i<=n;++i)
    {
        while(q>0 && a[q+1]!=a[i])
            q=pi[q];
        if(a[q+1]==a[i])
            ++q;
        pi[i]=q;
    }
}

int main ()
{
    freopen("reguli.in","r",stdin);
    freopen("reguli.out","w",stdout);
    int i,vf;

    scanf("%d%d",&n,&a[1]);
    for(i=2;i<=n;++i)
    {
        scanf("%d",&a[i]);
        a[i-1]=a[i]-a[i-1];
    }
    --n;

    kmp ();
    vf=n-pi[n];

    printf("%d\n",vf);
    for(i=1;i<=vf;++i)
        printf("%d\n",a[i]);
    return 0;
}