#include <cstdio>
 
using namespace std;
 
long long a[500001],x,y;
 
long n,i,rez,p[500001];
 
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;
    p[1]=0;
    for(i=2;i<=n;i++)
    {
        while(k>0 && a[k+1]!=a[i])
            k=p[k];
        p[i]=(k+=(a[k+1]==a[i]));
    }
    rez=n-p[n];
     
    printf("%ld\n",rez);
     
    for (i=1;i<=rez;++i)
        printf("%lld\n",a[i]);
     
    return 0;
}