n,pa,pb = input().split()
n = int(n)
pa,pb = int(round(float(pa)*1000)), int(round(float(pb)*1000))
*a, = map(int,input().split())
*b, = map(int,input().split())
a.sort()
b.sort()

from random import randrange
def check():
    d = 0
    aa = a[:]
    bb = b[:]
    for i in range(n):
        r = randrange(0,1000)
        if i == n-1 or r < pa:
            ca = aa.pop(0)
        else:
            r = randrange(1,n-i)
            ca = aa.pop(r)
        r = randrange(0,1000)
        if i == n-1 or r < pb:
            cb = bb.pop(0)
        else:
            r = randrange(1,n-i)
            cb = bb.pop(r)
        if ca > cb: d += ca+cb
        else: d -= ca+cb
    return d > 0

T = 200000
v = 0
for _ in range(T):
    v += check()
print(v/T)