#include<fstream>
using namespace std;

ifstream f("reguli.in");
ofstream g("reguli.out");

# define nmax 500005

int L[nmax],S[nmax],N;

void citire()
{
	int a,aa,i;
	f>>N>>aa;
	for(i=1;i<=N;++i)
		f>>a, S[i]=a-aa, aa=a;
}
void prefix()
{
	L[0]=L[1]=0;
	int i,k=0;
	for(i=2;i<N;++i)
	{
		while(k>0 && S[i]!=S[k+1]) k=L[k];
		if(S[i]==S[k+1]) ++k;
		L[i]=k;
	}
}
int main()
{
	citire();
	prefix();
	int i,l;
	l=N-1-L[N-1];
	g<<l<<'\n';
	for(i=1;i<=l;++i) g<<S[i]<<'\n';
	return 0;
}