Problem: 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.

Input

The first line contains a single integer n (1 ≤ n ≤ 100) — the number of Andrey's friends. The second line contains n real numbers pi (0.0 ≤ pi ≤ 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.

Output

Print a single real number — the probability that Andrey won't get upset at the optimal choice of friends. The answer will be considered valid if it differs from the correct one by at most 10 - 9.

Examples

Input

4
0.1 0.2 0.3 0.8


Output

0.800000000000


Input

2
0.1 0.2


Output

0.260000000000

Note

In the first sample the best strategy for Andrey is to ask only one of his friends, the most reliable one.

In the second sample the best strategy for Andrey is to ask all of his friends to come up with a problem. Then the probability that he will get exactly one problem is 0.1·0.8 + 0.9·0.2 = 0.26.

Solution (in JAVA):

Solution:


// package codeforces.contests.R253div1;

/**
 *
 * @author Abhishek Shankhadhar
 */
import java.io.*;
import java.util.*;
public class B {

    InputStream obj;
    PrintWriter out;
    String check = "";


    //Solution !!

    void solution() {
        int n=inti();
        double P[]=new double[n];
        for(int i=0;i<n;i++){
            P[i]=dou();
        }
        Arrays.sort(P);
        double p=1-P[n-1];
        double s=P[n-1]/(1-P[n-1]);
        double res=P[n-1];
        for(int i=n-2;i>=0;i--){
            double tem=p*P[i]*(1-s);
            if(tem>0)
                res+=tem;
            s+=(P[i]/(1-P[i]));
            p*=(1-P[i]);
        }
        out.println(res);
    }

    //------->ends !!


    public static void main(String[] args) throws IOException {
        new Thread(null, new Runnable() {
            public void run() {
                try {
                    new B().ace();
                } catch (IOException e) {
                    e.printStackTrace();
                } catch (StackOverflowError e) {
                    System.out.println("RTE");
                }
            }
        }, "1", 1 << 26).start();
    }

    
    void ace() throws IOException {
        out = new PrintWriter(System.out);
        obj = check.isEmpty() ? System.in : new ByteArrayInputStream(check.getBytes());
//        obj=check.isEmpty() ? new FileInputStream("location of file") : new ByteArrayInputStream(check.getBytes());
//        long t1=System.currentTimeMillis();
        solution();
//        long t2=System.currentTimeMillis();
//        out.println(t2-t1);
        out.flush();
        out.close();
    }
    byte inbuffer[] = new byte[1024];
    int lenbuffer = 0, ptrbuffer = 0;

    int readByte() {
        if (lenbuffer == -1) {
            throw new InputMismatchException();
        }
        if (ptrbuffer >= lenbuffer) {
            ptrbuffer = 0;
            try {
                lenbuffer = obj.read(inbuffer);
            } catch (IOException e) {
                throw new InputMismatchException();
            }
        }
        if (lenbuffer <= 0) {
            return -1;
        }
        return inbuffer[ptrbuffer++];
    }

    boolean isSpaceChar(int c) {
        return (!(c >= 33 && c <= 126));
    }

    String stri() {
        int b = skip();
        StringBuilder sb = new StringBuilder();
        while (!(isSpaceChar(b))) // when nextLine, (isSpaceChar(b) && b!=' ')
        {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }

    int skip() {
        int b;
        while ((b = readByte()) != -1 && isSpaceChar(b));
        return b;
    }

    int inti() {
        int num = 0, b;
        boolean minus = false;
        while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        while (true) {
            if (b >= '0' && b <= '9') {
                num = num * 10 + (b - '0');
            } else {
                return minus ? -num : num;
            }
            b = readByte();
        }
    }

    long loni() {
        long num = 0;
        int b;
        boolean minus = false;
        while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        while (true) {
            if (b >= '0' && b <= '9') {
                num = num * 10 + (b - '0');
            } else {
                return minus ? -num : num;
            }
            b = readByte();
        }
    }

    float fl() {
        return Float.parseFloat(stri());
    }

    double dou() {
        return Double.parseDouble(stri());
    }

    char chi() {
        return (char) skip();
    }

    int[] arri(int n) {
        int a[] = new int[n];
        for (int i = 0; i < n; i++) {
            a[i] = inti();
        }
        return a;
    }

    long[] arrl(int n) {
        long a[] = new long[n];
        for (int i = 0; i < n; i++) {
            a[i] = loni();
        }
        return a;
    }

    String[] stra(int n) {
        String a[] = new String[n];
        for (int i = 0; i < n; i++) {
            a[i] = stri();
        }
        return a;
    }

    private static void pa(Object... o) {
        System.out.println(Arrays.deepToString(o));
    }
//    uwi mod pow function

    public static long pow(long a, long n, long mod) {
//		a %= mod;
        long ret = 1;
        int x = 63 - Long.numberOfLeadingZeros(n);
        for (; x >= 0; x--) {
            ret = ret * ret % mod;
            if (n << 63 - x < 0) {
                ret = ret * a % mod;
            }
        }
        return ret;
    }

    int gcd(int a, int b) {
        if (a == 0) {
            return b;
        }
        return gcd(b % a, a);
    }
}