import sys
input = sys.stdin.readline

from time import time
time0=time()

from random import randint,random

N,PA,PB=map(float,input().split())
N=int(N)
A0=list(map(int,input().split()))
B0=list(map(int,input().split()))

LA=0
LB=0
while time()-time0<2.8:
    A=A0[:]
    B=B0[:]
    scorea=0
    scoreb=0

    for i in range(N):
        A.sort()
        B.sort()

        x=random()

        if x<PA or len(A)==1:
            ind=0
        else:
            ind=randint(1,len(A)-1)

        y=random()

        if y<PB or len(B)==1:
            ind2=0
        else:
            ind2=randint(1,len(B)-1)

        xa=A.pop(ind)
        xb=B.pop(ind2)

        if xa>xb:
            scorea+=xa+xb
        elif xa<xb:
            scoreb+=xa+xb

    if scorea>scoreb:
        LA+=1
    else:
        LB+=1

print(LA/(LA+LB))