Andrey needs one more problem to conduct a programming contest. He has *n* friends who are always willing to help. He can ask some of them to come up with a contest problem. Andrey knows one value for each of his fiends — the probability that this friend will come up with a problem if Andrey asks him.

Help Andrey choose people to ask. As he needs only one problem, Andrey is going to be really upset if no one comes up with a problem or if he gets more than one problem from his friends. You need to choose such a set of people that maximizes the chances of Andrey not getting upset.
The first line contains a single integer *n* (1 ≤ *n* ≤ 100) — the number of Andrey's friends. The second line contains *n* real numbers *p*<sub class="lower-index">*i*</sub> (0.0 ≤ *p*<sub class="lower-index">*i*</sub> ≤ 1.0) — the probability that the *i*-th friend can come up with a problem. The probabilities are given with at most 6 digits after decimal point.
def rl():
    return list(map(float,input().split()))
def ri():
    return int(input())
def rs():
    return input()
def rm():
    return map(int,input().split())

def main():
    n=ri()
    a=rl()
    a.sort(key=lambda x:-x)
    p=0
    for i in range(n):
        if p*(1-a[i])+(1-p)*a[i]>p:p=p*(1-a[i])+(1-p)*a[i]
        else: break
    return p
print(main())