d = int(input())
array = list(map(int, input().split()))
c = array[0]
f_1 = sum(array)
f_2 = 0
for i in range(d+1):
    if i % 2 == 0:
        f_2 += array[i]
    else:
        f_2 -= array[i]
for a in range(-1000, 1000):
    for b in range(-1000,1000):
        if a+b+c == f_1 and a-b+c == f_2:
            d = 3
            if a == 0:
                d -= 1
                if b == 0:
                    d -= 1
                    if c == 0:
                        d -= 1
            if d == 0:
                print(0)
                print(0)
                exit()
            print(d-1)
            for i in range(d):
                print([c,b,a][i], end=" ")
            exit()