백준 3046 Java

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Q3046 {

	public static void main(String[] args) throws IOException {
		BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
		String inp = bf.readLine();
		StringTokenizer st = new StringTokenizer(inp);
		int r1 = Integer.parseInt(st.nextToken());
		int s = Integer.parseInt(st.nextToken());
		
		int result = 2*s-r1;
		System.out.println(result);

	}

}