#yuki1237
mod=10**9+7
n=int(input())
l=list(map(int,input().split()))
if 0 in l:
 print(-1)
 exit()
if max(l)>3:
 print(mod)
s=[0,1,4,729]
res=1
for i in l:
 res*=s[i]
 if res>mod:
  print(mod)
  exit()
print(mod%res)