#yuki237
n=int(input())
a=list(map(int,input().split()))
if 0 in a:
 print(-1)
 exit()
if max(a)>=4:
 print(1000000007)
 exit()
res=1
x=[1,4,729]
for i in range(n):
 res*=x[a[i]-1]
 if res>1000000007:
  print(1000000007)
  break
 else:
  print(1000000007%res)