测试用例范围比较大，所以全部用long类型，如果用int类型只能通过60%，建议在内存和运行时间允许的情况下，比赛题都用long。

重点在于计算相交的面积，这里找的两个相交点是左上角（m1,n1）和右下角（m2,n2）

import java.util.*;
// 1:无需package
// 2: 类名必须Main, 不可修改

public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        long x1 = scan.nextInt();
        long y1 = scan.nextInt();
        long x2 = scan.nextInt();
        long y2 = scan.nextInt();
        long x3 = scan.nextInt();
        long y3 = scan.nextInt();
        long x4 = scan.nextInt();
        long y4 = scan.nextInt();

        long m1 = Math.max(Math.min(x1, x2), Math.min(x3, x4));
        long n1 = Math.min(Math.max(y1, y2), Math.max(y3, y4));
        long m2 = Math.min(Math.max(x1, x2), Math.max(x3, x4));
        long n2 = Math.max(Math.min(y1, y2), Math.min(y3, y4));

        long sum = 0;
        if (m1 < m2 && n1 > n2)
            sum = (m1 - m2) * (n1 - n2);
        long res = Math.abs((y2 - y1) * (x2 - x1)) + Math.abs((y3 - y4) * (x3 - x4)) + sum;
        System.out.println(res);
    }
}