#!/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())
z = d
while z > 2:
    a[z-2] += a[z]
    for i in reversed(range(3, z)):
        if a[i] != 0:
            z = i
            break
    else:
        break
res = rstrip(a[:3], 0)
print max(0, len(res) - 1)
print ' '.join(map(str, res)) or 0