#include <iostream>
#include <string>
#include <vector>
#include <cstdlib>
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <map>
#include <stack>
#include <queue>
#include <set>
#include <cstring>

using namespace std;
// ascending order
#define vsort(v) sort(v.begin(), v.end())
// descending order
#define vsort_r(v) sort(v.begin(), v.end(), greater<int>())
#define vunique(v) v.erase(unique(v.begin(), v.end()), v.end())
#define mp make_pair
#define ts(x) to_string(x)
#define rep(i, a, b) for(int i = (int)a; i < (int)b; i++)
#define repm(i, a, b) for(int i = (int)a; i > (int)b; i--)
#define bit(a) bitset<8>(a)
#define des_priority_queue priority_queue<int, vector<int>, greater<int> >
typedef long long ll;
typedef pair<int, int> P;
const ll INF = 1e18;

#define MAX_V 1000000
#define MAX_N 10

int n;
int a[MAX_N], b[MAX_N];

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);

  cin >> n;
  rep(i, 0, n) cin >> a[i];
  rep(i, 0, n) cin >> b[i];

  int array1[n], array2[n];
  rep(i, 0, n) {
    array1[i] = i;
    array2[i] = i;
  }

  int cntA = 0, cntB = 0, cntDraw = 0;
  do {
    do {
      int winA = 0, winB = 0, draw = 0;
      rep(i, 0, n) {
        int pointA = a[array1[i]], pointB = b[array2[i]];
        if(pointA > pointB) ++winA;
        else if(pointA < pointB) ++winB;
        else ++draw;
      }
      if(winA > winB) ++cntA;
      else if(winA < winB) ++cntB;
      else ++cntDraw;
    } while(next_permutation(array2, array2 + n));
  } while(next_permutation(array1, array1 + n));

  double rsl = cntA / (cntA + cntB + cntDraw + 0.0);
  cout << rsl << endl;
}