#!/usr/bin/python2
# -*- coding: utf-8 -*-
# †
n = int(raw_input())
b = [int(raw_input()) for _ in xrange(n)]
lo, hi = 1, 10**18
for i in xrange(n):
    if i & 1:
        lo, hi = max(lo - b[i], 1), hi - b[i]
    else:
        lo, hi = max(b[i] - hi, 1), b[i] - lo
if lo > hi:
    print -1
    exit(0)
a = [None] * n + [lo]
for i in reversed(xrange(n)):
    if i & 1:
        a[i] = b[i] + a[i+1]
    else:
        a[i] = b[i] - a[i+1]
print n + 1
print '\n'.join(map(str, a))