# include <cstdio>
using namespace std;
long long a[500001],x,y;
long i,n,pi[500001],sol;
int main()
{
    freopen("reguli.in","r",stdin);
    freopen("reguli.out","w",stdout);
    scanf("%ld%lld",&n,&x);n--;
    for(i=1;i<=n;++i)
    {
        scanf("%lld",&y);
        a[i]=y-x;
        x=y;
    }
    int k=0;
    pi[1]=1;
    for(i=2;i<=n;++i)
    {
        while(k>0 && a[k+1]!=a[i])
            k=pi[k];
        pi[i]=(k+=(a[k+1]==a[i]));
    }
    sol=n-pi[n];
    printf("%ld\n",sol);
    for(i=1;i<=sol;++i)
        printf("%lld\n",a[i]);
    return 0;
}