题解 | #牛牛的等差数列#

import java.util.Scanner;
public class Main{
    public static void main(String[]args){
        Scanner in =new Scanner(System.in);
        String input = in.nextLine();
        String []num=input.split(" ");
        int d=Integer.parseInt(num[1])-Integer.parseInt(num[0]);
        System.out.println(d+Integer.parseInt(num[1]));
    }
}