import sys
import numpy as np

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

N, PA, PB = readline().split()
N, PA, PB = int(N), float(PA), float(PB)
A = sorted(map(int, readline().split()))
B = sorted(map(int, readline().split()))

def compute_prob(N, P):
    # dp[i,j,k] = 残り1+i枚時点で、カードjが手元にある。それは手元の中でk番目である。
    dp = np.zeros((N, N, N))
    for j in range(N):
        dp[N - 1, j, j] = 1.0
    for i in range(N - 1, 0, -1):
        q = (1 - P) / i
        dp[i - 1] += q * dp[i] * np.arange(i, i - N, -1)[None, :]
        dp[i - 1, :, :-1] += dp[i, :, 1:] * (P + q * np.arange(N - 1))[None, :]
    # 提出確率に変更
    for i in range(N):
        if i == 0:
            p, q = 1.0, 0.0
        else:
            p, q = P, (1 - P) / i
        dp[i, :, 0] *= p
        dp[i, :, 1:] *= q
    return dp.sum(axis=2)

prob_a = compute_prob(N, PA)
prob_b = compute_prob(N, PB)

answer = 0
for j in range(N):
    for k in range(N):
        x, y = A[j], B[k]
        if x <= y:
            continue
        p = np.sum(prob_a[:, j] * prob_b[:, k])
        answer += p * (x + y)

print(answer)