import java.util.Scanner;

public class Main {

static Scanner scanner = new Scanner(System.in);

public static double computeRadio(int x1, int y1, int x2, int y2, int x3, int y3, int x4, int y4) {

//总共面积

int area = (x2 - x1) * (y2 -y1) + (x4 - x3) * (y4 - y3);

int width = Math.max(Math.min(x2, x4) - Math.max(x1, x3), 0);

int height = Math.max(Math.min(y2, y4) - Math.max(y1, y3), 0);

//交面积

double repeatArea=width * height;

//比值=交/并=交/（总-交）

return repeatArea/(area-repeatArea);

}

/*

* (x1,y1),(x2,y2)

* (x3,y3),(x4,y4)

*

* */

public static void main(String[] args) {

System.out.println("按格式输入：");

int x1=scanner.nextInt();

int y1=scanner.nextInt();

int x2=scanner.nextInt();

int y2=scanner.nextInt();

int x3=scanner.nextInt();

int y3=scanner.nextInt();

int x4=scanner.nextInt();

int y4=scanner.nextInt();

System.out.println(computeRadio(x1,y1,x2,y2,x3,y3,x4,y4));

}

}