#include <iostream> 
#include <sstream> 
#include <iomanip> 
#include <algorithm> 
#include <cmath> 
#include <string> 
#include <vector> 
#include <list> 
#include <queue> 
#include <stack> 
#include <set> 
#include <map> 
#include <bitset> 
#include <numeric> 
#include <climits> 
#include <cfloat> 
using namespace std; 

const double EPS = 1.0e-10;

class Point
{
public:
    double y, x;
    Point(){
        y = x = 0.0;
    }
    Point(double y0, double x0){
        y = y0;
        x = x0;
    }
    Point operator+(const Point& p) const{
        return Point(y + p.y, x + p.x);
    }
    Point operator-(const Point& p) const{
        return Point(y - p.y, x - p.x);
    }
    Point operator*(double a) const{
        return Point(y * a, x * a);
    }
    Point operator/(double a) const{
        return Point(y / a, x / a);
    }
    double cross(const Point& p) const{
        return x * p.y - y * p.x; // |a|*|b|*sinÆ
    }
};

class Line
{
public:
    double a, b, c; // a*x + b*y + c = 0
    Line(){
        a = c = 0.0;
        b = 1.0;
    }
    Line(double a0, double b0, double c0){
        a = a0;
        b = b0;
        c = c0;
    }
    Line(const Point& p1, const Point& p2){ // 2_ðÔ¼ü
        double dy = p2.y - p1.y;
        double dx = p2.x - p1.x;
        if(abs(dy / dx) < EPS){
            a = 0.0;
            b = 1.0;
            c = -p1.y;
        }else if(abs(dx / dy) < EPS){
            a = 1.0;
            b = 0.0;
            c = -p1.x;
        }else{
            a = - dy / dx;
            b = 1.0;
            c = dy / dx * p1.x - p1.y;
        }
    }
};

bool linesIntersection(const Line& l1, const Line& l2, Point& intersection)
{
    double s = l1.a*l2.b - l2.a*l1.b;
    if(abs(s) < EPS)
        return false;

    intersection = Point(l2.a*l1.c - l1.a*l2.c, l1.b*l2.c - l2.b*l1.c) / s;
    return true;
}

double polygonArea(const vector<Point>& p)
{
    int n = p.size();
    double ret = 0.0;
    for(int i=0; i<n; ++i)
        ret += p[i].cross(p[(i+1)%n]);
    return abs(ret) / 2.0;
}

int main()
{
    for(;;){
        int n;
        cin >> n;
        if(n == 0)
            return 0;

        vector<Point> a(n+2, Point(0, 0)), b(n+2, Point(1, 1)), c(n+2, Point(0, 0)), d(n+2, Point(1, 1));
        b[0] = Point(1, 0);
        a[n+1] = Point(0, 1);
        d[0] = Point(0, 1);
        c[n+1] = Point(1, 0);
        for(int i=1; i<=n; ++i)
            cin >> a[i].x;
        for(int i=1; i<=n; ++i)
            cin >> b[i].x;
        for(int i=1; i<=n; ++i)
            cin >> c[i].y;
        for(int i=1; i<=n; ++i)
            cin >> d[i].y;

        vector<Line> line1(n+2), line2(n+2);
        for(int i=0; i<n+2; ++i)
            line1[i] = Line(a[i], b[i]);
        for(int i=0; i<n+2; ++i)
            line2[i] = Line(c[i], d[i]);

        vector<vector<Point> > p(n+2, vector<Point>(n+2));
        for(int i=0; i<n+2; ++i){
            for(int j=0; j<n+2; ++j){
                linesIntersection(line1[i], line2[j], p[i][j]);
            }
        }

        double ret = 0.0;
        for(int i=0; i<n+1; ++i){
            for(int j=0; j<n+1; ++j){
                vector<Point> p1(4);
                p1[0] = p[i][j];
                p1[1] = p[i][j+1];
                p1[2] = p[i+1][j+1];
                p1[3] = p[i+1][j];
                ret = max(ret, polygonArea(p1));
            }
        }
        printf("%.10f\n", ret);
    }
}

Measured memory_bytes: 0