#include<stdio.h>
long n,i,m;
long long x,v,a[500005];
int main()
{
 freopen("reguli.in","r",stdin);
 freopen("reguli.out","w",stdout);
 scanf("%ld",&n);
 for(i=1;i<=n;++i)
    {scanf("%lld",&x);
     if(i>1)a[i-2]=x-v;
     v=x;}
 m=1;
 for(i=1;i<n-1;++i)
    if(a[i]!=a[i%m])
      if(a[i]==a[0])m=i;
        else m=i+1;
 printf("%ld\n",m);
 for(i=0;i<m;++i)
    printf("%ld\n",a[i]);
 return 0;
}