import sys

inf = 10**9 + 1

def solve():
    n = int(input())

    a_min = 1
    a_max = 10**18
    v = 0

    B = []

    for i in range(n):
        b = int(sys.stdin.readline().rstrip())
        B.append(b)

        if not (i & 1):
            v = -v

        if i & 1:
            v -= b
        else:
            v += b

        if (i >> 1) & 1:
            a_max = min(a_max, 10**18 - v)
            a_min = max(a_min, 1 - v)
        else:
            a_max = min(a_max, v - 1)
            a_min = max(a_min, v - 10**18)
            
    # print(a_min, a_max)

    if a_min > a_max:
        print(-1)
        return

    a = [0] * (n + 1)

    a[0] = a_min

    for i in range(1, n + 1):
        if i & 1:
            a[i] = B[i - 1] - a[i - 1]
        else:
            a[i] = a[i - 1] - B[i - 1]

    print(n + 1)
    print(*a, sep='\n')

if __name__ == '__main__':
    solve()