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

#define _p(...) (void)printf(__VA_ARGS__)
#define forr(x,arr) for(auto&& x:arr)
#define _overload3(_1,_2,_3,name,...) name
#define _rep2(i,n) _rep3(i,0,n)
#define _rep3(i,a,b) for(int i=int(a);i<int(b);++i)
#define rep(...) _overload3(__VA_ARGS__,_rep3,_rep2,)(__VA_ARGS__)
#define _rrep2(i,n) _rrep3(i,0,n)
#define _rrep3(i,a,b) for(int i=int(b)-1;i>=int(a);i--)
#define rrep(...) _overload3(__VA_ARGS__,_rrep3,_rrep2,)(__VA_ARGS__)
#define ALL(x) (x).begin(), (x).end()
#define BIT(n) (1LL<<(n))
#define SZ(x) ((int)(x).size())
#define fst first
#define snd second
typedef vector<int> vi;typedef vector<vi> vvi;typedef pair<int,int> pii;typedef vector<pii> vpii;
typedef long long ll;

int N;
double pa, pb;
vi A, B;

void shuffle(double p, vi &cards) {
  rep(round, N - 1) {
    int ci = 0;
    rep(i, 1, N - round) {
      if (cards[i] < cards[ci]) {
        ci = i;
      }
    }

    double r = (rand() % 1000) / 1000.0;
    if (r >= p) {
      int ri = rand() % (N-round-1);
      if (ri >= ci) ri++;
      ci = ri;
    }
    swap(cards[ci], cards[N-round-1]);
  }
}

int game() {
  int a = 0, b = 0;

  shuffle(pa, A);
  shuffle(pb, B);

  rep(i, N) {
    if (A[i] > B[i]) a += A[i] + B[i];
    else b += A[i] + B[i];
  }
  /*
  cout << "A:"; rep(ii,SZ(A)) cout << ' ' << A[ii]; cout << endl;
  cout << "B:"; rep(ii,SZ(B)) cout << ' ' << B[ii]; cout << endl;
  cout<<"a: "<<a<<endl;
  cout<<"b: "<<b<<endl;
  */

  if (a > b) return 1;
  else if (b > a) return -1;
  else return 0;
}

void Main() {
  srand(time(0));
  cin >> N >> pa >> pb;
  A.resize(N);
  B.resize(N);
  rep(i, N) cin >> A[i];
  rep(i, N) cin >> B[i];

  int a = 0, b = 0;

  rep(_, 1000000) {
    int r = game();
    if (r == 1) a += 1;
    else if (r == -1) b += 1;
  }

  _p("%.8f\n", 1.0*a/(a+b));
}
int main() { cin.tie(0); ios::sync_with_stdio(false); Main(); return 0; }