#include <bits/stdc++.h>
using namespace std;

mt19937 mt;

vector<int> vec(vector<int> V, double P) {
    vector<int> ret;

    while (V.size()) {
        int N = V.size();
        if (N == 1 || (mt() % 10000) / 10000.0 < P) {
            ret.push_back(V[0]);
            V.erase(V.begin());
        } else {
            int n = (mt() % (N - 1)) + 1;
            auto it = V.begin() + n;
            ret.push_back(*it);
            V.erase(it);
        }
    }

    return ret;
}

int main() {
    int N;
    double PA, PB;
    vector<int> A, B;
    cin >> N >> PA >> PB;
    for (int i = 0; i < N; i++) {
        int a;
        cin >> a;
        A.emplace_back(a);
    }
    for (int i = 0; i < N; i++) {
        int b;
        cin >> b;
        B.emplace_back(b);
    }
    sort(A.begin(), A.end());
    sort(B.begin(), B.end());

    const int LOOP = 1000000;
    int cnt_a = 0;
    for (int i = 0; i < LOOP; i++) {
        auto VA = vec(A, PA);
        auto VB = vec(B, PB);
        int a = 0, b = 0;
        for (int j = 0; j < N; j++) {
            if (VA[j] > VB[j]) {
                a += VA[j] + VB[j];
            } else if (VA[j] < VB[j]) {
                b += VA[j] + VB[j];
            }
        }
        if (a > b)
            cnt_a++;
    }

    cout << (double)cnt_a / (LOOP) << endl;
}