D = int(input())
lsa = list(map(int,input().split()))
if D <= 2:
    print(D)
    print(*lsa,sep=' ')
    exit()

for i in range(D-2,0,-1):
    lsa[i] += lsa[i+2]
    lsa[i+2] = 0

lsans = lsa[:3]
if lsans.count(0) == 3:
    print(0)
    print(0)
    exit()

for i in range(2,-1,-1):
    if lsans[i] != 0:
        D = i
        break
print(D)
print(*lsans[:D+1],sep=' ')