#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); i++)
#define irep(i, n) for (int i = (n); i >= 0; i--)
using namespace std;
using ll = long long;
using P = pair<int, int>;
const int INF = 1 << 25;
const int MOD = 1e9+7;

int fact(int x) {
	if (x == 0) return 1;
	return x * fact(x-1);
}
int a[10], b[10];
int main() {
	int n;
	cin >> n;
	rep(i,n) cin >> a[i];
	rep(i,n) cin >> b[i];

	sort(a,a+n);
	sort(b,b+n);

	int cnt = 0;
	do
	{
		do
		{
			int win = 0;
			rep(i,n) {
				if (a[i] > b[i]) win++;
			}
			if (win > n-win) cnt++; 
		} while (next_permutation(b,b+n));
	} while (next_permutation(a,a+n));
	
	double ans = 1.*cnt / (fact(n)*fact(n));
	cout << ans << endl;
	return 0;
}