#include <bits/stdc++.h>

using namespace std;

void potato() {
  int n;
  cin >> n;
  vector<double> a(n), b(n);
  for(auto& x : a) cin >> x;
  for(auto& x : b) cin >> x;
  sort(a.begin(), a.end());
  sort(b.begin(), b.end());

  double wins = 0, rounds = 0;
  do {
    do {
      int aw = 0, bw = 0;
      for(int i = 0; i < n; i++) {
        if(a[i] > b[i]) aw++;
        else bw++;
      }
      if(aw > bw) wins++;
      rounds++;
    } while(next_permutation(b.begin(), b.end()));
  } while(next_permutation(a.begin(), a.end()));

  double ans = wins / rounds;
  printf("%.6lf\n", ans);
}

signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int tt=1;
  while(tt--) potato();
  return 0;
}