#include <cstdio>
#include <climits>
#include <algorithm>
using namespace std;

class range {private: struct I{int x;int operator*(){return x;}bool operator!=(I& lhs){return x<lhs.x;}void operator++(){++x;}};I i,n;
public:range(int n):i({0}),n({n}){}range(int i,int n):i({i}),n({n}){}I& begin(){return i;}I& end(){return n;}};

const int N = 624;
const int M = 397;
const unsigned int MATRIX_A = 0x9908b0dfU;
const unsigned int UPPER_MASK = 0x80000000U;
const unsigned int LOWER_MASK = 0x7fffffffU;

vector<unsigned int> mt;
int mti = N + 1;

void init_genrand(unsigned int s) {
  mt.push_back(s & 0xffffffffU);
  for(mti=1; mti<N; mti++) {
    mt.push_back(1812433253U * (mt[mti-1] ^ (mt[mti-1] >> 30)) + mti);
    mt[mti] &= 0xffffffffU;
  }
}

void init_by_array(vector<unsigned int> init_key) {
  int key_length = init_key.size();
  init_genrand(19880731U); // まいぷる
  int i = 1, j = 0;
  int k = N > key_length ? N : key_length;
  for( ; k; k--) {
    mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1664525U)) + init_key[j] + j;
    mt[i] &= 0xffffffffU;
    i++; j++;
    if(i >= N) { mt[0] = mt[N-1]; i = 1; }
    if(j >= key_length) { j = 0; }
  }
  for(k=N-1; k; k--) {
    mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1566083941U)) - i;
    mt[i] &= 0xffffffffU;
    i++;
    if(i >= N) { mt[0] = mt[N-1]; i = 1; }
  }
  mt[0] = 0x80000000U;
}

unsigned int genrand_int32(void) {
  unsigned int y;
  static unsigned int mag01[2] = {0x0U, MATRIX_A};
  if(mti >= N) {
    if(mti == N + 1) { init_genrand(5489U); }
    int kk;
    for(kk=0; kk<N-M; kk++) {
      y = (mt[kk] & UPPER_MASK) | (mt[kk+1] & LOWER_MASK);
      mt[kk] = mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1U];
    }
    for(; kk<N-1; kk++) {
      y = (mt[kk] & UPPER_MASK) | (mt[kk+1] & LOWER_MASK);
      mt[kk] = mt[kk+(M-N)] ^ (y >> 1) ^ mag01[y & 0x1U];
    }
    y = (mt[N-1] & UPPER_MASK) | (mt[0] & LOWER_MASK);
    mt[N-1] = mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1U];
    mti = 0;
  }
  y = mt[mti++];
  y ^= (y >> 11);
  y ^= (y << 7) & 0x9d2c5680U;
  y ^= (y << 15) & 0xefc60000U;
  y ^= (y >> 18);
  return y;
}

int genrand_int31(void) {
  return (int)(genrand_int32() >> 1);
}

double genrand_real2(void) {
  return genrand_int32()*(1.0/4294967296.0);
}

int choose(vector<int> &v, float prob) {
  int pos;
  if(genrand_real2() < prob) {
    pos = 0;
  } else {
    pos = genrand_int31() % (v.size() - 1) + 1;
  }
  int res = v[pos];
  v.erase(v.begin() + pos);
  return res;
}

int main(void) {
  clock_t start = clock();
  time_t seed = time(0);
  vector<unsigned int> init;
  init.push_back(0x123);
  init.push_back(0x234);
  init.push_back(0x345);
  init.push_back(0x456);
  init.push_back(seed);
  init_by_array(init);

  int n;
  float pa, pb;
  scanf("%d%f%f", &n, &pa, &pb);
  vector<int> a, b;
  for(int i : range(n)) { int x; scanf("%d", &x); a.push_back(x); }
  for(int i : range(n)) { int x; scanf("%d", &x); b.push_back(x); }
  sort(a.begin(), a.end());
  sort(b.begin(), b.end());

  int game, win;
  int limit = 2.8 * CLOCKS_PER_SEC;
  for(game=0, win=0; clock()-start < limit; game++) {
    vector<int> cpa = a, cpb = b;
    int suma = 0, sumb = 0;
    for(int i : range(n-1)) {
      int ca = choose(cpa, pa);
      int cb = choose(cpb, pb);
      if(ca > cb) { suma += ca+cb; }
      else { sumb += ca+cb; }
    }
    int ca = cpa[0], cb = cpb[0];
    if(ca > cb) { suma += ca+cb; }
    else { sumb += ca+cb; }
    if(suma > sumb) { win++; }
  }
  printf("%f\n", float(win) / game);
  return 0;
}