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 = []

for x in map(fr, input().split()):
    ans = max(ans, x)
    a.append(x)

ans2 = 0
for i in range(n):
    cur = a[i]
    for j in range(n):
        if i != j:
            cur *= 1 - a[j]
    ans2 += cur

ans = max(ans, ans2)


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