from collections import *
from itertools import *
from functools import *
from heapq import *
import sys, math, random, time

# input = sys.stdin.readline
start = time.time()

N, pa, pb = input().split()
N = int(N)
pa = float(pa)
pb = float(pb)
A = list(map(int, input().split()))
B = list(map(int, input().split()))
cnt = 0
win = 0
A.sort()
B.sort()


def f():

    X = deque(A[:])
    Y = deque(B[:])

    a = 0
    b = 0
    while X:
        if len(X) == 1:
            if X[0] > Y[0]:
                a += X[0] + Y[0]
            elif X[0] < Y[0]:
                b += X[0] + Y[0]
            break

        if random.random() < pa:
            vx = X.popleft()
        else:
            vx = X[random.randint(1, len(X) - 1)]
            X.remove(vx)
        if random.random() < pb:
            vy = Y.popleft()
        else:
            vy = Y[random.randint(1, len(Y) - 1)]
            Y.remove(vy)
        if vx > vy:
            a += vx + vy
        if vx < vy:
            b += vx + vy
    return a > b


while time.time() - start < 2.5:

    win += f()
    cnt += 1
print(win / cnt)