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.
import fractions
import operator
import functools


def calc(d, nd, n):

    r = 0
    for i in range(n):

        r += d[i] * functools.reduce(operator.mul, nd[:i] + nd[i + 1:n], 1)

    return r


n = int(input())
x = tuple(sorted(map(fractions.Fraction, str.split(input())), reverse=True))
nx = tuple(map(lambda p: 1 - p, x))

p = 0
for i in range(1, n + 1):

    p = max(p, calc(x[:i], nx[:i], i))

print(float(p))
