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 sys
input=sys.stdin.readline
n=int(input())
p=list(map(float,input().split()))
p.sort(reverse=True)
max_p=0
for i in range(n):
    score=0
    for j in range(i+1):
        c=1
        for k in range(i+1):
            if j==k:
                c*=p[k]
            else:
                c*=1-p[k]
        score+=c
    if score>=max_p:
        max_p=score
    else:
        break
print(max_p)