#include "bits/stdc++.h"
using namespace std;
#define int long long
#define FOR(i, a, b) for(int i=(a);i<(b);i++)
#define RFOR(i, a, b) for(int i=(b-1);i>=(a);i--)
#define REP(i, n) for(int i=0; i<(n); i++)
#define RREP(i, n) for(int i=(n-1); i>=0; i--)
#define ALL(a) (a).begin(),(a).end()
#define UNIQUE_SORT(l) sort(ALL(l)); l.erase(unique(ALL(l)), l.end());
#define CONTAIN(a, b) find(ALL(a), (b)) != (a).end()
#define array2(type, x, y) array<array<type, y>, x>
#define vector2(type) vector<vector<type> >
#define out(...) printf(__VA_ARGS__)

int dxy[] = {0, 1, 0, -1, 0};

/*================================*/

int N,M,L;
double Pa, Pb;

int choice(vector<int> *V, double p) {
    if ((*V).size() == 1 || ((double)rand()/RAND_MAX) <= p) {
        return (*V)[0];
    } else {
        return (*V)[(rand() % ((*V).size() - 1)) + 1];
    }
}

signed main()
{
#if DEBUG
    std::ifstream in("input.txt");
    std::cin.rdbuf(in.rdbuf());
#endif
    cin>>N>>Pa>>Pb;
    vector<int> A(N),B(N);
    REP(i,N)cin>>A[i];
    REP(i,N)cin>>B[i];
    sort(ALL(A));
    sort(ALL(B));
    
    srand((unsigned int)time(NULL));
    double ans = 0;
    REP(i,1e6) {
        auto Ac = A;
        auto Bc = B;
        int score = 0;
        REP(j,N) {
            int a = choice(&Ac, Pa);
            int b = choice(&Bc, Pb);
            if (a > b) {
                score += a + b;
            } else if (b > a) {
                score -= a + b;
            }
            Ac.erase(std::remove(Ac.begin(), Ac.end(), a), Ac.end());
            Bc.erase(std::remove(Bc.begin(), Bc.end(), b), Bc.end());
        }
        if (score > 0) ans++;
    }
    
    cout << ans / 1e6 << endl;
    
    return 0;
}