D=int(input())
a=list(map(int,input().split()))
if D==0:
    print(0)
    print(a[0])
    exit()
for i in range(D,2,-1):
    a[i-2]+=a[i]
if a[2]:
    print(2)
    print(a[0],a[1],a[2])
elif a[1]:
    print(1)
    print(a[0],a[1])
else:
    print(0)
    print(a[0])