import sys

sys.setrecursionlimit(10 ** 6)
def LI(): return list(map(int, sys.stdin.readline().split()))

from random import *

def game(xx, yy, n, pa, pb):
    sx = sy = 0
    for _ in range(n - 1):
        m = len(xx)
        if randrange(1000) < pa: i = m - 1
        else: i = randrange(m - 1)
        if randrange(1000) < pb: j = m - 1
        else: j = randrange(m - 1)
        if xx[i] > yy[j]: sx += xx[i] + yy[j]
        else: sy += xx[i] + yy[j]
        del xx[i]
        del yy[j]
    if xx[0] > yy[0]: return sx + xx[0] + yy[0] > sy
    else: return sx > sy + xx[0] + yy[0]

def main():
    n, pa, pb = input().split()
    n = int(n)
    pa = int(pa[2:])
    pb = int(pb[2:])
    aa = LI()
    bb = LI()
    aa.sort(reverse=True)
    bb.sort(reverse=True)
    loop = 50000
    win = 0
    for _ in range(loop):
        if game(aa[:], bb[:], n, pa, pb): win += 1
    print(win / loop)

main()