D=int(raw_input())
a = map(int, raw_input().split())
for i in range(len(a)-1,2,-1):
    a[i-2] += a[i]
    a[i] = 0

d=0
for i in range( min(2,len(a)-1), -1,-1 ):
    if (a[i]!=0 or i==0):
        print i
        d=i+1
        break
for i in range(d):
    print a[i],
print