D = int(raw_input())
b = map(int, raw_input().split())

for a in xrange(D, 2, -1):
    b[a - 2] += b[a]
    b[a] = 0

while len(b) > 0:
    if b[-1] == 0:
        del b[-1]
    else:
        break

if len(b) == 0:
    print 0
    print 0
else:
    print len(b) - 1
    print " ".join(map(str, b))