D = input()
a = map(int,raw_input().split())
for i in xrange(D,2,-1):
	a[i-2] += a[i]
	a[i] = 0
D2 = 0
for i in xrange(min(3,D+1)):
	if a[i] != 0:
		D2 = i
print D2
print " ".join(str(a[i]) for i in xrange(D2+1))