import sys

def input(): return sys.stdin.readline().strip()
def list2d(a, b, c): return [[c] * b for i in range(a)]
def list3d(a, b, c, d): return [[[d] * c for j in range(b)] for i in range(a)]
def list4d(a, b, c, d, e): return [[[[e] * d for j in range(c)] for j in range(b)] for i in range(a)]
def ceil(x, y=1): return int(-(-x // y))
def INT(): return int(input())
def MAP(): return map(int, input().split())
def LIST(N=None): return list(MAP()) if N is None else [INT() for i in range(N)]
def Yes(): print('Yes')
def No(): print('No')
def YES(): print('YES')
def NO(): print('NO')
sys.setrecursionlimit(10 ** 9)
INF = 10 ** 19
MOD = 10 ** 9 + 7
EPS = 10 ** -10

N = INT()
A = LIST()

if N <= 2:
    print(N)
    print(*A)
    exit()

A = A[::-1]
B = [1, 0, -1, 0]
for i in range(N-4+2):
    a = A[i]
    cur = [0] * 4
    for j in range(4):
        cur[j] = B[j] * a
    for j in range(4):
        A[i+j] -= cur[j]
ans = []
for i in range(N):
    if A[i] != 0:
        ans = A[i:]
        break
ans = ans[::-1]
if ans:
    print(len(ans)-1)
    print(*ans)
else:
    print(0)
    print(0)