#coding: utf-8
##yuki_40

n=int(raw_input())
a=map(int,raw_input().split())

f0=a[0] #f(x)=b2*x**2+b1*x+b0
f1=0
f2=0

for i in xrange(n+1):
 f1+=a[i]

for i in xrange(n+1):
 if i%2==0:
  f2+=a[i]
 else:
  f2-=a[i]

b0=f0
b1=(f1-f2)/2
b2=(f1+f2)/2-f0
if b2!=0:
 print 2
elif b2==0 and b1!=0:
 print 1
else:
 print 0

if b2==0:
 b2=''
if b1==0:
 b1=''
print b0,b1,b2