#!/usr/bin/env python3.8
# %%
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
import random

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


# %%
def select_card(A, P):
    if len(A) == 1:
        return 0
    p = random.random()
    if p < P:
        return 0
    n = len(A)
    return random.randint(1, n - 1)


# %%
def simulate(N, A, B):
    SA = 0
    SB = 0
    for _ in range(N):
        i = select_card(A, PA)
        j = select_card(B, PB)
        a = A.pop(i)
        b = B.pop(j)
        if a > b:
            SA += a + b
        elif a < b:
            SB += a + b
    return SA > SB


# %%
n_trial = 10 ** 5
win = sum(simulate(N, A[:], B[:]) for _ in range(n_trial))
print(win / n_trial)