import random

N, PA, PB = input().split()
A = list(map(int, input().split()))
B = list(map(int, input().split()))
A.sort(reverse=True)
B.sort(reverse=True)

N = int(N)
PA, PB = int(float(PA) * 1000) , int(float(PB) * 1000)
win = 0

def f(L, P):
    temp = []
    for i in range(N):
        v = random.randint(1, 1000)
        if v <= P or i == N - 1:
            temp.append(L.pop())
        else:
            ind = random.randint(0, len(L) - 2)
            temp.append(L.pop(ind))
    return temp

for _ in range(10 ** 6):
    LA, LB = [], []
    for i in range(N):
        LA.append(A[i])
        LB.append(B[i])
        
    VA = f(LA, PA)
    VB = f(LB, PB)
    SA, SB = 0, 0
    for a, b in zip(VA, VB):
        if a > b:
            SA += a + b
        else:
            SB += a + b
    if SA > SB:
        win += 1
    
print(win/10**6)