p=print
n=int(input())
b=[int(input())for _ in[0]*n]
i=m=-1
a=[1]*-~n
while i<n:
 i+=1;a[i+1]=[b[i]-a[i],a[i]-b[i]][i%2]
 if 0>=a[i+1]or a[i+1]>10**18:a[0]+=-a[i+1]+1;i=-1;m+=1
 if m==10:break
if 0>=a[0]or m==10:p(-1);exit()
p(n+1)
for _ in a:p(_)