# your code goes here
D=int(input())
a=[int (i) for i in input (). split ()]
while len(a)>3:
    a[2]+=a[0]
    a.pop(0)
  #  print (a)
print (len(a)-1)
i=len(a)-1
b=""
while i>=0:
    b+=str(a[i])+" "
    i-=1
print (b)