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.
from decimal import Decimal as fr


ans = 0

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

ans = max(a)


def calc(lst):
    global ans

    prod = 1
    for i in range(len(lst)):
        prod *= 1 - lst[i]
        cur = 0
        for j in range(i + 1):
            cur += lst[j] * prod / (1 - lst[j])

#        print(cur)
        ans = max(ans, cur)


lst = list(sorted(filter(lambda x: x < 0.5, a)))

calc(lst)
calc(lst[::-1])


print('{:.15f}'.format(ans))
