#include <cstdio>

 #include <cstring>

 #include <cmath>

 #include <algorithm>

 const int maxn =  + ;

 struct HEHE

 {

     double a, b, c, d;

 }hehe[maxn];

 struct Point

 {

     double x, y;

     Point(double x=, double y=):x(x), y(y) {}

 };

 typedef Point Vector;

 Vector operator - (const Vector& A, const Vector& B)

 { return Vector(A.x - B.x, A.y - B.y); }

 double Cross(const Vector& A, const Vector& B)

 { return (A.x*B.y - A.y*B.x); }

 Point GetIntersection(const double& a, const double& b, const double& c, const double& d)

 {

     double x = (a+(b-a)*c) / (-(b-a)*(d-c));

     double y = (d-c)*x+c;

     return Point(x, y);

 }

 int main(void)

 {

     //freopen("2402in.txt", "r", stdin);

     int n;

     while(scanf("%d", &n) ==  && n)

     {

         memset(hehe, , sizeof(hehe));

         for(int i = ; i <= n; ++i) scanf("%lf", &hehe[i].a);

         for(int i = ; i <= n; ++i) scanf("%lf", &hehe[i].b);

         for(int i = ; i <= n; ++i) scanf("%lf", &hehe[i].c);

         for(int i = ; i <= n; ++i) scanf("%lf", &hehe[i].d);

         hehe[n+].a = hehe[n+].b = hehe[n+].c = hehe[n+].d = 1.0;

         double ans = 0.0;

         for(int i = ; i <= n; ++i)

             for(int j = ; j <= n; ++j)

             {

                 Point A, B, C, D;

                 A = GetIntersection(hehe[i].a, hehe[i].b, hehe[j].c, hehe[j].d);

                 B = GetIntersection(hehe[i+].a, hehe[i+].b, hehe[j].c, hehe[j].d);

                 C = GetIntersection(hehe[i+].a, hehe[i+].b, hehe[j+].c, hehe[j+].d);

                 D = GetIntersection(hehe[i].a, hehe[i].b, hehe[j+].c, hehe[j+].d);

                 double temp = 0.0;

                 temp += Cross(B-A, C-A) / ;

                 temp += Cross(C-A, D-A) / ;

                 ans = std::max(ans, temp);

             }

         printf("%.6f\n", ans);

     }

     return ;

 }