n = int(raw_input())
l = map(int, raw_input().split())
for i in range(n, 2, -1):
    l[i-2] += l[i]
    l[i] = 0
i = n
while i >= 0 and l[i] == 0:
    i -= 1
i = max(i,0)
print i
print ' '.join(map(str, l[:i+1]))