#include <algorithm>
#include <iostream>
#include <cstdio>
#include <map>
#include <numeric>
#include <cmath>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#include <queue>
#include <stack>
#include <complex>
#include <string.h>
#include <unordered_set>
#include <unordered_map>
#include <bitset>
#include <iomanip>
#include <sys/time.h>
#include <tuple>
#include <random>
using namespace std;

#define endl '\n'
#define ALL(v) (v).begin(), (v).end()
#define RALL(v) (v).rbegin(), (v).rend()
#define UNIQ(v) (v).erase(unique((v).begin(), (v).end()), (v).end())

typedef long long ll;
typedef long double ld;
typedef pair<int, int> P;
typedef complex<double> comp;
typedef vector< vector<ld> > matrix;
struct pairhash {
public:
    template<typename T, typename U>
    size_t operator()(const pair<T, U> &x) const {
	size_t seed = hash<T>()(x.first);
	return hash<U>()(x.second) + 0x9e3779b9 + (seed<<6) + (seed>>2);
    }
};
const int inf = 1e9 + 9;
const ll mod = 1e9 + 7;
const double eps = 1e-8;
const double pi = acos(-1);

int n;
double p[2];
int a[2][20];

unsigned long xor128(void) {
    static unsigned long x=123456789,y=362436069,z=521288629,w=88675123;
    unsigned long t;
    t=(x^(x<<11));x=y;y=z;z=w; return( w=(w^(w>>19))^(t^(t>>8)) );
}

int rand(int k) {
    if (k <= 0) return 0;
    return xor128() % k;
}

int q[2];
bool win() {
    q[0] = q[1] = 0;
    int s[2];
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < 2; j++) {
            sort(a[j], a[j]+n-i);
            if (i == n-1 || (double)rand(inf) / inf < p[j]) s[j] = 0;
            else s[j] = rand(n-i-1) + 1;
        }
        
        if (a[0][s[0]] > a[1][s[1]]) q[0] += a[0][s[0]] + a[1][s[1]];
        else q[1] += a[0][s[0]] + a[1][s[1]];
        for (int j = 0; j < 2; j++)
            swap(a[j][s[j]], a[j][n-i-1]);
    }
    return q[0] > q[1];
}

double solve() {
    int d = 700000, c = 0;
    for (int x = 0; x < d; x++) {
        c += win();
    }
    return (double)c / d;
}

void input() {
    cin >> n >> p[0] >> p[1];
    for (int j = 0; j < 2; j++)
        for (int i = 0; i < n; i++)
            cin >> a[j][i];
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(15);

    input();
    cout << solve() << endl;
}