d = int(input())
A = list(map(int, input().split()))

if d <= 2:
    print(d)
    print(*A)
    exit()

A.reverse()
D = [1, 0, -1, 0]
for i in range(d - 2):
    r = 0
    for j in range(4):
        if j == 0:
            r = A[i + j] // D[j]
        else:
            A[i + j] -= r * D[j]
ANS = A[d - 2:d + 2]
while len(ANS) > 1 and ANS[0] == 0:
    ANS.pop(0)
ANS.reverse()
print(len(ANS) - 1)
print(*ANS)