mod = 1000000007
eps = 10**-9


def main():
    import sys
    input = sys.stdin.readline

    N = int(input())
    A = list(map(int, input().split()))
    if 0 in A:
        print(-1)
    else:
        f = 1
        B = []
        for i in range(1, 10**5):
            f *= i
            new = i ** f
            if new > mod:
                break
            B.append(new)
        ans = 1
        for a in A:
            if a > len(B):
                print(mod)
                exit()
            ans *= B[a-1]
            if ans > mod:
                print(mod)
                exit()
        print(mod % ans)


if __name__ == '__main__':
    main()