#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
using ll = long long; using ull = unsigned long long; using pil = pair<int, ll>; using pli = pair<ll, int>;
template <typename T> using piT = pair<int, T>; template <typename T> using pTi = pair<T, int>; template <typename T> using pTT = pair<T, T>;
using pii = pair<int, int>; using vi = vector<int>; using vvi = vector<vi>; using vvvi = vector<vvi>;
using pll = pair<ll, ll>; using vl = vector<ll>; using vvl = vector<vl>; using vvvl = vector<vvl>;
using pbb = pair<bool, bool>; using vb = vector<bool>; using vvb = vector<vb>; using vvvb = vector<vvb>;
using pcc = pair<char, char>; using vc = vector<char>; using vvc = vector<vc>; using vvvc = vector<vvc>;
using pss = pair<string, string>; using vs = vector<string>; using vvs = vector<vs>; using vvvs = vector<vvs>;
using pdd = pair<double, double>; using vd = vector<double>; using vvd = vector<vd>; using vvvd = vector<vvd>;
#define rep0(times) for(int counter = 0; counter < (int)(times); ++counter)
#define rep(counter, goal) for (int counter = 0; counter < (int)(goal); ++counter)
#define rep2(counter, start, goal) for (int counter = (int)(start); counter < (int)(goal); ++counter)
#define rep3(counter, start, goal) for (int counter = (int)(start); counter > (int)(goal); --counter)
#define all(container) begin(container), end(container)
template <typename T> bool chmax(T &x, const T &y) { if (x < y) { x = y; return true; } return false; }
template <typename T> bool chmin(T &x, const T &y) { if (x > y) { x = y; return true; } return false; }
void Yn(bool flag) { cout << (flag ? "Yes" : "No") << "\n"; }
void yn(bool flag) { cout << (flag ? "yes" : "no") << "\n"; }
void YN(bool flag) { cout << (flag ? "YES" : "NO") << "\n"; }
void set_prec(const int &digits) { cout << fixed << setprecision(digits); cerr << fixed << setprecision(digits); }
// #include <atcoder/all>
// using namespace atcoder;
// void pr(const atcoder::modint1000000007 &obj) { cerr << obj.val(); };
// void pr(const atcoder::modint998244353 &obj) { cerr << obj.val(); };
// void pr(const atcoder::modint &obj) { cerr << obj.val(); };
template <typename T> void pr(const T &obj) { cerr << obj; }
template <typename T, typename ...Ts> void pr(const T &first, const Ts &...rest) { pr(first); pr(", "); pr(rest...); }
template <typename S, typename T> void pr(const pair<S, T> &pair) { pr("("); pr(pair.first); pr(", "); pr(pair.second); pr(")"); }
template <typename T> void pr(const vector<T> &vec) { pr("{"); for (T obj : vec) { pr(obj); pr(", "); } pr("}"); }
template <typename T> void pr(const vector<vector<T>> &vv) { pr("\n"); rep(index, vv.size()) { pr("["); pr(index); pr("]: "); pr(vv[index]); pr("\n"); } }
template <typename T> void pr(const set<T> &vec) { pr("{"); for (T obj : vec) { pr(obj); pr(", "); } pr("}"); }
template <typename S, typename T> void pr(const map<S, T> &map) { pr("{"); for (pair<S, T> pair : map) { pr("("); pr(pair.first); pr(": "); pr(pair.second); pr("), "); } pr("}"); }
#define db(obj) cerr << #obj << ": "; pr(obj); cerr << " "
#define dl(obj) db(obj); cerr << "\n";
#define dm(...) cerr << "(" << #__VA_ARGS__ << "): ("; pr(__VA_ARGS__); cerr << ") "
#define dml(...) dm(__VA_ARGS__); cerr << "\n"
// const ll MOD = 1000000007;
// using mint = modint1000000007;
// const ll MOD = 998244353;
// using mint = modint998244353;
// using mint = modint;

vi A_cards, B_cards;
int A_wins = 0;

void permutation(int n) {
	assert(n >= 0);
	vi p; rep(i, n) p.push_back(i);
	do {
		int A_point = 0, B_point = 0;
		rep(j, n) {
			if (A_cards[j] > B_cards[p[j]]) ++A_point;
			else if (A_cards[j] < B_cards[p[j]]) ++B_point;
		}
		if (A_point > B_point) ++ A_wins;
	} while (next_permutation(all(p)));
}

int main() {
	int N; cin >> N;
	A_cards = B_cards = vi(N);
	rep(i, N) cin >> A_cards[i];
	rep(i, N) cin >> B_cards[i];
	permutation(N);
	double ans = A_wins;
	rep2(i, 1, N + 1) ans /= i;
	cout << ans << endl;
}