def read_data():
    N, Pa, Pb = input().split()
    N = int(N)
    Pa = float(Pa)
    Pb = float(Pb)
    As = list(map(int, input().split()))
    Bs = list(map(int, input().split()))
    return N, Pa, Pb, As, Bs


def solve(N, PA, PB, As, Bs):
    As.sort()
    Bs.sort()
    pa = calc_occurence_rates(N, PA)
    pb = calc_occurence_rates(N, PB)
    score = 0
    for i, ai in enumerate(As):
        for j, bj in enumerate(Bs):
            if ai <= bj:
                break
            p = sum(paik * pbjk for paik, pbjk in zip(pa[i], pb[j]))
            score += (ai + bj) * p
    return score


def calc_occurence_rates(N, p):
    dp = [[[0] * (N - i) for _ in range(N)] for i in range(N)]
    for i in range(N):
        dp[0][i][i] = 1.0
    for k in range(1, N):
        pp = (1.0 - p) / (N - k)
        for i in range(N):
            dpki = dp[k][i]
            prev = dp[k-1][i]
            for j in range(N - k):
                dpki[j] += prev[j] * pp * (N - k - j)  # jより大きいカードが選ばれた
                dpki[j] += prev[j + 1] * (p + pp * j)  # j+1より小さいカードが選ばれた
    survived = [list(map(sum, dpk)) for dpk in dp]
    for k in range(N-1):
        sk = survived[k]
        for i, skki in enumerate(survived[k + 1]):
            sk[i] -= skki
    return list(zip(*survived))


if __name__ == '__main__':
    N, Pa, Pb, As, Bs = read_data()
    print(solve(N, Pa, Pb, As, Bs))