#!/usr/bin/python
from itertools import dropwhile
rstrip = lambda arr, p: list(reversed(list(dropwhile(lambda x: x == p, reversed(arr)))))

d = int(raw_input())
a = map(int, raw_input().split())
for i in xrange(d, 2, -1):
    a[i-2] += a[i]
res = rstrip(a[:3], 0)
print max(0, len(res) - 1)
print ' '.join(map(str, res)) or 0