import random

N,Pa,Pb=map(float,raw_input().split())
N=int(N)
As=map(int,raw_input().split())
Bs=map(int,raw_input().split())
As.sort()
Bs.sort()
n_win=0
for i in range(500000):
    A=[a for a in As]
    B=[b for b in Bs]
    Ascore=0
    Bscore=0
    for j in range(N):
        a=A[0]
        b=B[0]
        if len(A)==1 or random.random()<=Pa:
            del A[0]
        else:
            ai=random.randint(1,len(A)-1)
            a=A[ai]
            del A[ai]
        if len(B)==1 or random.random()<=Pb:
            del B[0]
        else:
            bi=random.randint(1,len(B)-1)
            b=B[bi]
            del B[bi]
        if a>b:
            Ascore+=a+b
        else:
            Bscore+=a+b
    if Ascore>Bscore:
        n_win+=1
print n_win*1.0/500000