백준 #6749번 Next in line

import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in);
		
		int a = sc.nextInt();
		int b = sc.nextInt();
		int c = b - a;
		b = b + c;
		
		System.out.println(b);
		sc.close();
	}
}