#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
//using mint = modint998244353;
//const int mod = 998244353;
//const int INF = 1e9;
//const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n) - 1; i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r) - 1;i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define P pair<int,int>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int n; cin >> n;
	vector<double>x(n), y(n), z(n), w(n);
	rep(i, n)cin >> x[i] >> y[i];
	rep(i, n)cin >> z[i] >> w[i];
	double gx = 0, gy = 0, gz = 0, gw = 0;
	rep(i, n) {
		gx += x[i];
		gy += y[i];
		gz += z[i];
		gw += w[i];
	}
	cout << fixed << setprecision(16);
	gx /= n;
	gy /= n;
	gz /= n;
	gw /= n;
	double dxy = 0, dzw = 0;
	auto dist = [](double x0, double y0, double x1, double y1)->double {
		double dx = x1 - x0;
		double dy = y1 - y0;
		return sqrt(dx * dx + dy * dy);
	};
	rep(i, n) {
		dxy += dist(x[i], y[i], gx, gy);
		dzw += dist(z[i], w[i], gz, gw);
	}
	double ans = dzw / dxy;
	cout << ans << endl;
	return 0;
}