#!/usr/bin/env python3
n = int(input())
b = [ int(input()) for _ in range(n) ]
def f(a1):
    a = [ None ] * (n+1)
    a[0] = a1
    for i in range(n):
        if (i+1 + 1) % 2 == 0:
            a[i+1] = - a[i] + b[i]
        else:
            a[i+1] = a[i] - b[i]
    return a
lower = 1
upper = 10**18
a = f(0)
for i in range(n+1):
    if ((i+1) // 2) % 2 == 0:
        lower = max(lower, 1      - a[i])
        upper = min(upper, 10**18 - a[i])
    else:
        lower = max(lower, a[i] - 10**18)
        upper = min(upper, a[i] - 1     )
if lower <= upper:
    print(n+1)
    for ai in f(lower):
        print(ai)
else:
    print(-1)