n=int(input())
b=[int(input()) for _ in range(n)]
i=m=0
a=[1]*(n+1)
while i<n:
 if i%2:a[i+1]=a[i]-b[i]
 else:a[i+1]=b[i]-a[i]
 if a[i+1]<=0:a[0]=-a[i+1]+1;i=-1;m+=1
 if m==1000:print(-1);exit()
 i+=1
if a[0]<=0:print(-1);exit()
print(n+1)
for _ in range(n+1):print(a[_])