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

class Depo
{
	public static void main (String[] args) throws java.lang.Exception
	{
		double n;
		double x, p=1;
		double cs, sc;
		Scanner in = new Scanner(System.in);
		x=in.nextDouble();
		n=in.nextDouble();
		cs= sc = Math.cos(Math.abs(x));
		for(int k=1; k<=n; k++){
			p*= (k / (k + 1)) - cs;
		    cs*=sc;
		}
		System.out.println(p);
	}
}