题解 | 构造C的歪

根据等差数列的性质，直接使用b-(a-b)

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scanner=new Scanner(System.in);
		int a=scanner.nextInt();
		int b=scanner.nextInt();
		System.out.println(b-(a-b));

	}

}