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

import sys
if D == 0:
    print(0)
    print(a[0])
    exit()
for i in range(3,D+1):
    if i % 2 == 1:
        a[1] += a[i]
    else:
        a[2] += a[i]
a = a[:3]
while a and a[-1] == 0:
    a.pop()
if not a:
    print(0)
    print(0)
else:
    print(len(a) - 1)
    print(*a)