n = int(input())
b = [int(input()) for _ in range(n)] 


for index, elm in enumerate(b):
	if index == 0:
		begin = 1
		end = elm - begin
		key = elm
	elif index%2:
		key = key - elm
		end = min(end, key-1)
	else:
		key = elm - key
		end = min(end, elm - key)
	if end < begin:
		print(-1)
		exit()

for index, elm in enumerate(b):
	if index == 0:
		key = begin
		print(key)
		key = elm - key
		print(key)
		continue
	if index%2:
		key = key - elm
		print(key)
	else:
		key = elm - key
		print(key)