import math


def main():
    N = int(input())
    A = list(map(int, input().split()))

    mod = 10 ** 9 + 7

    if 0 in A:
        return -1
    for a in A:
        if a >= 4:
            return mod
    ans = 1
    for a in A:
        ans *= a ** math.factorial(a)
    return mod % ans


print(main())