n=int(input())
B=[int(input()) for i in range(n)]

MINUS=[]
PLUS=[]

c=0
now=0

for i in range(n):
    if c==0 or c==1:
        if c==0:
            now=-now+B[i]
        else:
            now-=B[i]
        MINUS.append(now)
        
    else:
        if c==2:
            now=-now+B[i]
        else:
            now-=B[i]
        PLUS.append(now)
        

    c+=1
    c%=4

ANS=[max(1,-min(PLUS)+1)]
for i in range(n):
    if i%2==0:
        ANS.append(B[i]-ANS[-1])
    else:
        ANS.append(ANS[-1]-B[i])

if min(ANS)<=0:
    print(-1)
else:
    print(n+1)
    for ans in ANS:
        print(ans)