#include <bits/stdc++.h>
#define rep(i, a) for (int i = 0; i < (a); i++)
#define rep2(i, a, b) for (int i = (a); i < (b); i++)
#define repr(i, a) for (int i = (a) - 1; i >= 0; i--)
#define repr2(i, a, b) for (int i = (b) - 1; i >= (a); i--)
using namespace std;
typedef long long ll;
const ll inf = 1e9;
const ll mod = 1e9 + 7;

struct XorShift {
	unsigned z;
	XorShift() : z((unsigned)time(NULL)) {}
	XorShift(int seed) : z(z) {}
	unsigned next() {
		z ^= z << 13;
		z ^= z >> 17;
		z ^= z << 5;
		return z;
	}
	unsigned nextInt(unsigned a, unsigned b) {
		return next() % (b - a + 1) + a;
	}
	double nextDouble() {
		return next() / (double)(1ll << 32);
	}
};

bool usedA[10], usedB[10];

int main() {
	int N;
	double PA, PB;
	cin >> N >> PA >> PB;
	vector<int> A(N), B(N);
	rep (i, N) cin >> A[i];
	rep (i, N) cin >> B[i];
	sort(A.begin(), A.end());
	sort(B.begin(), B.end());
	int winA = 0;
	int winB = 0;

	XorShift random;
	const int C = 2e5;
	rep (ii, C) {
		int a = 0;
		int b = 0;
		vector<int> X(A), Y(B);

		rep (i, N) {
			int ia, ib;
			if (i == N - 1 || random.nextDouble() <= PA) {
				ia = 0;
			} else {
				ia = random.nextInt(1, X.size() - 1);
			}

			if (i == N - 1 || random.nextDouble() <= PB) {
				ib = 0;
			} else {
				ib = random.nextInt(1, Y.size() - 1);
			}

			if (X[ia] > Y[ib]) {
				a += X[ia] + Y[ib];
			} else {
				b += X[ia] + Y[ib];
			}

			X.erase(X.begin() + ia);
			Y.erase(Y.begin() + ib);
		}

		if (a > b) winA++;
		if (a < b) winB++;
	}

	double ans = (double)winA / C;
	printf("%.20f\n", ans);
}