#include <iostream>
#include <stdio.h>

using namespace std;

double p[4][32];


double CalcArea(double x1, double y1,
		double x2, double y2,
		double x3, double y3,
		double x4, double y4 )
{
  return ((x2-x1)*(y3-y1)+(x4-x2)*(y3-y2)-(y2-y1)*(x3-x1)-(y4-y2)*(x3-x2))/2;
}

/*
double CalcArea(double x1, double y1,
		double x2, double y2,
		double x3, double y3,
		double x4, double y4 )
{
  double a, b, c, d, x, y;
  a = x2 - x1;
  c = y2 - y1;
  b = x3 - x1;
  d = y3 - y1;
  //cout << "test = "  << a*d - b*c << endl;
  x = (x4 - x1) / (a + b);
  y = (y4 - y1) / (c + d);
  double xpy = x4/(a+b) + y4/(c+d) - x1/(a+b) - y1/(c+d);
  //double xpy = x4/(a+c) + y4/(b+d) - x1/(a+c) - y1/(b+d);
  return (a*d-b*c) * (xpy) / 2;
}
*/

/*
double CalcArea(double x1, double y1,
		double x2, double y2,
		double x3, double y3,
		double x4, double y4 )
{
  double dx1, dx2;
  dx1 = x2 - x1 - (x3 - x1)*(y2 - y1)/(y3 - y1);
  dx2 = x4 - x3 - (x3 - x1)*(y4 - y3)/(y3 - y1);
  return (dx1 + dx2) * (y3 - y1) / 2;
}
*/

void CalcPoint(double a, double b, double c, double d, double *x, double *y)
{
  *x = (a + (b-a)*c) / (1 - (b-a)*(d-c));
  *y = (d-c)*(*x) + c;
  //cout << "(" << *x << ", " << *y << ")" << endl;
  /*for(int i=0; i<100; i++){
    double xx, yy;
    xx = a - (a-b)*(*y);
    yy = c - (c-d)*(*x);
    (*x) = xx;
    (*y) = yy;
  }*/
  return;
}

int main()
{
  int n;
  while((cin >> n) && n){
    for(int i=0; i<4; i++){
      p[i][0] = 0.0;
      for(int j=1; j<=n; j++){
	double buf;
	cin >> buf;
	p[i][j] = buf;
      }
      p[i][n+1] = 1.0;
    }

    double areamax = 0.0;
    for(int i=0; i<=n; i++){
      for(int j=0; j<=n; j++){
	double x1,y1, x2,y2, x3,y3, x4,y4;
	CalcPoint(p[0][i],   p[1][i],   p[2][j],   p[3][j],   &x1, &y1);
	CalcPoint(p[0][i+1], p[1][i+1], p[2][j],   p[3][j],   &x2, &y2);
	CalcPoint(p[0][i],   p[1][i],   p[2][j+1], p[3][j+1], &x3, &y3);
	CalcPoint(p[0][i+1], p[1][i+1], p[2][j+1], p[3][j+1], &x4, &y4);
	double area = CalcArea(x1,y1, x2,y2, x3,y3, x4,y4);
	//cout << i << "," << j << "  area=" << area << endl;
	if(areamax < area) areamax = area;
      }
    }

    printf("%6f\n", areamax);
  }
  return 0;
}