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]
a = ((f_1+f_2) - 2*c)//2
for b in range(-1000000, 1000000):
    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()