fact = [1]
for i in range(1, 5):
    fact.append(fact[-1] * i)


n = int(input())
a = list(map(int, input().split()))
MOD = 10 ** 9 + 7

if 0 in a:
    print(-1)
    exit()

flag = False
ans = 1
for val in a:
    if val > 4:
        flag = True
        break
    ans *= val ** fact[val]
    if ans > MOD:
        flag = True
        break

if flag:
    print(MOD)
else:
    print(MOD % ans)