import java.util.*;
import java.io.*;

public class y {
	static public void main(String[] args) throws Exception {
		new y().run();
	}
	public void run() throws Exception {
		Scanner in = new Scanner(System.in);
		
		long t = System.currentTimeMillis();
		in.next();
		in.next();
		System.out.println((System.currentTimeMillis()-t) * 1e-3);
	}
}