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.
n = int(input())
P = list(map(float, input().split()))
Q = []
for i in P:
    Q.append(1 - i)
Q.sort()
ans = 0
c1 = 1
c2 = 0
for i in Q:
    if (c1 * i) * (c2 + 1 / i - 1) > ans:
         ans = (c1 * i) * (c2 + 1 / i - 1)
         c1 *= i
         c2 += (1 / i - 1)
print(ans)