/**
 * Start at 21:20
 * End at 22:40
 * Problem: poj1408
 * Author: __560
 *
 */
#include<iostream>
#include<cstdlib>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<math.h>

using namespace std;

const int maxn=1000100;
const int INF=(1<<28);
const double eps=0.00000000001;

int n;
struct Point
{
    double x,y;
    friend double operator*(Point A,Point B)
    {
        return A.x*B.y-A.y*B.x;
    }
    friend Point operator-(Point A,Point B)
    {
        return {A.x-B.x,A.y-B.y};
    }
    friend Point operator+(Point A,Point B)
    {
        return {A.x+B.x,A.y+B.y};
    }
};
Point A[maxn],B[maxn],C[maxn],D[maxn];

Point inter_point(Point A,Point B,Point C,Point D)
{
    double a=fabs((B-A)*(C-A));
    double b=fabs((B-A)*(D-A));
    double x=(a*D.x+b*C.x)/(a+b);
    double y=(a*D.y+b*C.y)/(a+b);
    return {x,y};
}

void solve()
{
    double ans=0;
    A[0]=C[0]={0,0};
    B[0]=C[n+1]={0,1};
    D[0]=A[n+1]={1,0};
    B[n+1]=D[n+1]={1,1};
    for(int i=0;i<=n;i++){
        for(int j=0;j<=n;j++){
            Point a=inter_point(A[i],B[i],C[j],D[j]);
            Point b=inter_point(A[i+1],B[i+1],C[j],D[j]);
            Point c=inter_point(A[i],B[i],C[j+1],D[j+1]);
            Point d=inter_point(A[i+1],B[i+1],C[j+1],D[j+1]);
            double area=(b-a)*(d-a)/2.0+(d-a)*(c-a)/2.0;
            if(area>ans+eps) ans=area;
            //cout<<"a= "<<a.x<<" "<<a.y<<" ";
            //cout<<"i="<<i<<" j="<<j<<" area="<<area<<endl;
        }
    }
    printf("%.6f\n",ans);
}

int main()
{

    while(cin>>n,n){
        for(int i=1;i<=n;i++){
            scanf("%lf",&(A[i].x));
            A[i].y=0;
        }
        for(int i=1;i<=n;i++){
            scanf("%lf",&(B[i].x));
            B[i].y=1;
        }
        for(int i=1;i<=n;i++){
            scanf("%lf",&(C[i].y));
            C[i].x=0;
        }
        for(int i=1;i<=n;i++){
            scanf("%lf",&(D[i].y));
            D[i].x=1;
        }
        solve();
    }
    return 0;
}