n = int(input())
a = list(map(int,input().split()))

def fact(n):
    ret = 1
    for i in range(1,n+1):
        ret *= i
    return ret

if min(a) == 0:
    print(-1)
elif max(a) >= 4:
    print(10**9 + 7)

else:
    ans = 1
    for x in a:
        ans *= x**fact(x)
        if ans >= 10**9 + 7:
            print(10**9 + 7)
            exit()
    print((10**9 + 7)%ans)