_ = input()
a = list(map(int, input().split()))

while len(a) > 3:
    tail = a.pop(-1)
    a[-2] += tail
    while len(a) > 0 and a[-1] == 0:
        a.pop(-1)
    
if len(a) == 0:
    print("0")
    print("0")
else:
    print(len(a) - 1)
    print(" ".join(map(str, a)))