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 itertools

def max_probability_of_not_getting_upset(n, probabilities):
    max_probability = 0.0

    for i in range(n):
        # Calculate the probability of getting exactly one problem from friend i
        probability_i = probabilities[i]
        other_probabilities = [probabilities[j] for j in range(n) if j != i]
        probability_one_problem = probability_i * (1 - sum(other_probabilities))

        # Update the maximum probability
        max_probability = max(max_probability, probability_one_problem)

    return max_probability

# Read input
n = int(input())
probabilities = list(map(float, input().split()))

# Calculate the maximum probability of not getting upset
result = max_probability_of_not_getting_upset(n, probabilities)
print('{:.12f}'.format(result))
