#include<iostream>
#include<string>
#include<cstdio>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<complex>
#include<bitset>
#include<stack>
#include<unordered_map>
using namespace std;
typedef long long ll;
typedef unsigned int ui;
const ll mod = (ll)(1e+9) + 7;
const ll INF = (ll)1000000007 * 1000000007;
typedef pair<int, int> P;
#define stop char nyaa;cin>>nyaa;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
typedef long double ld;
typedef complex<ld> Point;
const ld eps = 1e-8;
const ld pi = acos(-1.0);
typedef pair<ll, ll> LP;
typedef pair<ld, ld> LDP;
const int key = 100000;
int a[20], b[20];
int main() {
	cout << fixed << setprecision(8);
	random_device rd;
	mt19937 mt(rd());
	int n; cin >> n; ld pA, pB;
	cin >> pA >> pB; pA *= 1000; pB *= 1000;
	int pa = (int)pA, pb = (int)pB;
	rep(i, n) {
		cin >> a[i];
	}
	rep(i, n) {
		cin >> b[i];
	}
	int cnt = 0;
	rep(aa, key) {
		vector<int> v,va,vb;
		rep(i, n) {
			v.push_back(a[i]);
		}
		sort(v.begin(), v.end());
		rep(i, n-1) {
			int sum = pa * (n-i-1) + (1000 - pa)*(n-i-1);
			uniform_int_distribution<> rnd(0, sum-1);
			int x = rnd(mt);
			if (x <= pa * (n - i-1)) {
				va.push_back(v[0]);
				v.erase(v.begin());
			}
			else {
				int id = (x - pa * (n - i-1)) / (1000-pa)+1;
				va.push_back(v[id]);
				v.erase(v.begin() + id);
			}
		}
		va.push_back(v[0]); v.clear();
		rep(i, n) {
			v.push_back(b[i]);
		}
		sort(v.begin(), v.end());
		rep(i, n-1) {
			int sum = pb * (n - i-1) + (1000 - pb)*(n-i-1);
			uniform_int_distribution<> rnd(0, sum-1);
			int x = rnd(mt);
			if (x <= pb * (n - i-1)) {
				vb.push_back(v[0]);
				v.erase(v.begin());
			}
			else {
				int id = (x - pb * (n - i-1)) / (1000-pb) + 1;
				vb.push_back(v[id]);
				v.erase(v.begin() + id);
			}
		}
		vb.push_back(v[0]); v.clear();
		int ca = 0, cb = 0;
		rep(i, n) {
			if (va[i] > vb[i]) {
				ca += va[i] + vb[i];
			}
			else if (va[i] < vb[i]) {
				cb += va[i] + vb[i];
			}
		}
		if (ca > cb)cnt++;
	}
	cout << cnt / (ld)key << endl;
	return 0;
}