#include <cstdio>

using namespace std;
long long int v[500005];
int main()
{
    freopen("reguli.in","r",stdin);
    freopen("reguli.out","w",stdout);
    int n,i,m;
    long long int last,x;
    scanf ("%d",&n);
    last=0;
    for (i=0;i<n;i++)
    {
        scanf ("%lld",&x);
        if (i==0)
        {
            last=x;
        }
        else
        {
            v[i]=x-last;
            last=x;
        }
    }
    m=2;
    while (v[m]!=v[1])
        m++;
        m--;
    printf("%d\n",m);
    for (i=1;i<=m;i++)
        printf ("%lld\n",v[i]);
    /*
    for (j=2;j<=n;j++)
    {
        w[j]=v[j]-v[j-1];
    }
    */
    return 0;
}