MOD = 1000000007

def main():
    _ = int(input())
    a = [int(x) for x in input().split()]
    if min(a)==0:
        print("-1")
        return
    elif max(a)>=4:
        print(MOD)
        return
    res = 1
    f = [1,1,2,6]
    for v in a:
        for _ in range(f[v]):
            res *= v
            if res > MOD:
                print(MOD)
                return
    print(MOD%res)


if __name__ == "__main__":
    main()