import sys
read=sys.stdin.buffer.read
readline=sys.stdin.buffer.readline
readlines=sys.stdin.buffer.readlines

npapb=readline().split()
n=int(npapb[0])
pa=float(npapb[1])
pb=float(npapb[2])
a0=list(map(int, readline().split()))
b0=list(map(int, readline().split()))
a0.sort()
b0.sort()
cnt=0
import random
for _ in range(100000):
    sa, sb=0, 0
    a=a0[:]
    b=b0[:]
    for i in range(n):
        if i==n-1:
            if a[0]>b[0]:
                sa+=a[0]+b[0]
            else:
                sb+=a[0]+b[0]
            break
        ra=random.random()
        rb=random.random()
        ia, ib=0, 0
        if ra>pa:
            ia=random.randint(1, n-i-1)
        if rb>pb:
            ib=random.randint(1, n-i-1)
        a1=a[ia]
        b1=b[ib]
        if a1>b1:
            sa+=a1+b1
        else:
            sb+=a1+b1
        a.remove(a1)
        b.remove(b1)
    if sa>sb:
        cnt+=1
print(cnt/100000.0)