// Problem D : Rotation Estimation

#include <iostream>
#include <vector>
#include <complex>
#include <algorithm>
#include <cmath>
#include <stdio.h>

using namespace std;

const double EPS = 1e-8;
typedef complex<double> P;
double rot(P a, P b) { return arg(conj(a)*b); }

namespace std{
	bool operator < (const P &a, const P &b){
		return make_pair(real(a),imag(a)) < make_pair(real(b),imag(b));
	}
}

int main(){
	int n;
	while(cin >> n, n){
		vector<P> vp1(n), vp2(n);
		P g1 = P(0,0), g2 = P(0,0);
		double x, y;
		for(int i=0;i<n;i++){
			cin >> x >> y; vp1[i] = P(x,y);
			g1 += vp1[i];
		}
		for(int i=0;i<n;i++){
			cin >> x >> y; vp2[i] = P(x,y);
			g2 += vp2[i];
		}
		g1 /= n;
		g2 /= n;
		// 重心を重ね合わせる
		for(int i=0;i<n;i++){
			vp1[i] -= g1;
			vp2[i] -= g2;
		}
		sort(vp1.begin(), vp1.end());
		double ans = 1e12;
		for(int i=0;i<n;i++){
			// 原点からの距離が等しい点について，実際に回して確かめてみる
			if(abs(abs(vp1[0])-abs(vp2[i])) < EPS){
				double r = rot(vp2[i], vp1[0]);
				vector<P> tmp(n);
				for(int j=0;j<n;j++){					
					tmp[j] = P(real(vp2[j])*cos(r)-imag(vp2[j])*sin(r),real(vp2[j])*sin(r)+imag(vp2[j])*cos(r));
				}
				sort(tmp.begin(), tmp.end());
				bool flag = true;
				for(int j=0;j<n;j++){
					flag &= (abs(vp1[j]-tmp[j]) < EPS);
				}
				if(flag) ans = min(ans, abs(r));
			}
		}
		printf("%.10lf\n", ans);
	}
}