n=int(input())
a=list(map(int,input().split()))
if min(a)==0:
  print(-1)
  exit(0)
if 4<=max(a):
  print(m)
  exit(0)
m=10**9+7
x=1
for i in a:
  if i==1:
    continue
  y=1
  for j in range(1,i+1):
    y*=j
  for k in range(y):
    x*=i
    if m<x:
      print(m)
      exit(0)
print(m%x)